Install fails on Python 3.5 because of zipp requiring Python 3.6

/etc/os-release

PRETTY_NAME="Raspbian GNU/Linux 9 (stretch)"
NAME="Raspbian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
VERSION_CODENAME=stretch
ID=raspbian
ID_LIKE=debian
HOME_URL="http://www.raspbian.org/"
SUPPORT_URL="http://www.raspbian.org/RaspbianForums"
BUG_REPORT_URL="http://www.raspbian.org/RaspbianBugs"

Collecting silkaj
  Downloading https://files.pythonhosted.org/packages/f5/a5/3ab8d193fa836945088462be5c5168bb135a77e4e6b1f802bb97f00db11e/silkaj-0.7.6-py3-none-any.whl (44kB)
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Collecting duniterpy==0.55.1 (from silkaj)
  Downloading https://files.pythonhosted.org/packages/2f/91/91e52b55ba53f85e7ccce267789fec6ebf8b43faa46225e3d75eb6077898/duniterpy-0.55.1-py3-none-any.whl (70kB)
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Collecting Click (from silkaj)
  Downloading https://files.pythonhosted.org/packages/fa/37/45185cb5abbc30d7257104c434fe0b07e5a195a6847506c074527aa599ec/Click-7.0-py2.py3-none-any.whl (81kB)
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Collecting ipaddress (from silkaj)
  Downloading https://files.pythonhosted.org/packages/c2/f8/49697181b1651d8347d24c095ce46c7346c37335ddc7d255833e7cde674d/ipaddress-1.0.23-py2.py3-none-any.whl
Collecting pynacl (from silkaj)
  Downloading https://www.piwheels.org/simple/pynacl/PyNaCl-1.3.0-cp35-cp35m-linux_armv7l.whl (543kB)
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Collecting tabulate (from silkaj)
  Downloading https://www.piwheels.org/simple/tabulate/tabulate-0.8.6-py3-none-any.whl
Collecting texttable (from silkaj)
  Downloading https://files.pythonhosted.org/packages/ec/b1/8a1c659ce288bf771d5b1c7cae318ada466f73bd0e16df8d86f27a2a3ee7/texttable-1.6.2-py2.py3-none-any.whl
Collecting pylibscrypt>=1.7.1 (from duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/pylibscrypt/pylibscrypt-1.8.0-py3-none-any.whl
Collecting attr>=0.3.1 (from duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/attr/attr-0.3.1-py3-none-any.whl
Collecting libnacl>=1.6.1 (from duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/08/51/02fde6692edf1b3fcb1520de8ef1dbe9306157ad7e86a3c36882a5f30c67/libnacl-1.7.1-py2.py3-none-any.whl
Collecting aiohttp>=3.3.2 (from duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/c2/f7/f0ad3dbace4762fef5d80aa4124b41bf218e4c4dd6d387a86cede707d9a4/aiohttp-3.6.2-py3-none-any.whl (441kB)
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Collecting jsonschema>=2.6.0 (from duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/c5/8f/51e89ce52a085483359217bc72cdbf6e75ee595d5b1d4b5ade40c7e018b8/jsonschema-3.2.0-py2.py3-none-any.whl (56kB)
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Collecting pypeg2>=2.15.2 (from duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/pypeg2/pyPEG2-2.15.2-py3-none-any.whl
Collecting base58>=1.0.0 (from duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/ac/03/52b4d529a1ba2f006be395a1b9ff6e1ab83875b84e1dc67343362edaff05/base58-2.0.0-py3-none-any.whl
Collecting pyaes>=1.6.1 (from duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/pyaes/pyaes-1.6.1-py3-none-any.whl
Collecting cffi>=1.4.1 (from pynacl->silkaj)
  Downloading https://www.piwheels.org/simple/cffi/cffi-1.14.0-cp35-cp35m-linux_armv7l.whl (315kB)
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Requirement already satisfied: six in /usr/lib/python3/dist-packages (from pynacl->silkaj)
Collecting yarl<2.0,>=1.0 (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/yarl/yarl-1.4.2-cp35-cp35m-linux_armv7l.whl (234kB)
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Collecting attrs>=17.3.0 (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/a2/db/4313ab3be961f7a763066401fb77f7748373b6094076ae2bda2806988af6/attrs-19.3.0-py2.py3-none-any.whl
Requirement already satisfied: chardet<4.0,>=2.0 in /usr/lib/python3/dist-packages (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
Collecting async-timeout<4.0,>=3.0 (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/e1/1e/5a4441be21b0726c4464f3f23c8b19628372f606755a9d2e46c187e65ec4/async_timeout-3.0.1-py3-none-any.whl
Collecting multidict<5.0,>=4.5 (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/multidict/multidict-4.7.4-cp35-cp35m-linux_armv7l.whl (131kB)
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Collecting idna-ssl>=1.0; python_version < "3.7" (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/idna-ssl/idna_ssl-1.1.0-py3-none-any.whl
Collecting typing-extensions>=3.6.5; python_version < "3.7" (from aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/03/92/705fe8aca27678e01bbdd7738173b8e7df0088a2202c80352f664630d638/typing_extensions-3.7.4.1-py3-none-any.whl
Requirement already satisfied: setuptools in /usr/lib/python3/dist-packages (from jsonschema>=2.6.0->duniterpy==0.55.1->silkaj)
Collecting pyrsistent>=0.14.0 (from jsonschema>=2.6.0->duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/pyrsistent/pyrsistent-0.15.7-cp35-cp35m-linux_armv7l.whl (103kB)
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Collecting importlib-metadata; python_version < "3.8" (from jsonschema>=2.6.0->duniterpy==0.55.1->silkaj)
  Downloading https://files.pythonhosted.org/packages/8b/03/a00d504808808912751e64ccf414be53c29cad620e3de2421135fcae3025/importlib_metadata-1.5.0-py2.py3-none-any.whl
Collecting pycparser (from cffi>=1.4.1->pynacl->silkaj)
  Downloading https://www.piwheels.org/simple/pycparser/pycparser-2.19-py2.py3-none-any.whl (111kB)
    100% |████████████████████████████████| 112kB 994kB/s 
Requirement already satisfied: idna>=2.0 in /usr/lib/python3/dist-packages (from yarl<2.0,>=1.0->aiohttp>=3.3.2->duniterpy==0.55.1->silkaj)
Collecting zipp>=0.5 (from importlib-metadata; python_version < "3.8"->jsonschema>=2.6.0->duniterpy==0.55.1->silkaj)
  Downloading https://www.piwheels.org/simple/zipp/zipp-2.1.0-py3-none-any.whl
zipp requires Python '>=3.6' but the running Python is 3.5.3