[mod] #60: Drop Python 3.5 support

- CI: Raise container Python version to v3.6
- pyproject.toml: Set v3.6 as minimal supported version

.gitlab-ci.yml

@@ -7,7 +7,7 @@ stages:
 
 variables:
   DOCKER_IMAGE: "registry.duniter.org/docker/python3/poetry"
-  PYTHON_VERSION: "3.5"
+  PYTHON_VERSION: "3.6"
 
 image: $DOCKER_IMAGE/$PYTHON_VERSION:latest
 
@@ -114,4 +114,4 @@ pages:
       when: manual
     - if: $CI_COMMIT_BRANCH == "master"
       when: manual
-    - when: never
\ No newline at end of file
+    - when: never

pyproject.toml

@@ -24,7 +24,7 @@ requires = ["poetry>=0.12"]
 build-backend = "poetry.masonry.api"
 
 [tool.poetry.dependencies]
-python = "^3.5.3"
+python = "^3.6.8"
 aiohttp = "^3.6.1"
 jsonschema = "^3.0.2"
 pypeg2 = "^2.15.2"
@@ -35,7 +35,7 @@ libnacl = "^1.6.1"
 pyaes = "^1.6.1"
 
 [tool.poetry.dev-dependencies]
-black = { version = "^19.3b0", python = "^3.6" }
+black = "^19.3b0"
 mypy = "^0.730"
 pylint = "^2.4.2"
 sphinx = "^3.0.2"