[dep] Update websocket-client and attrs to major releases

ws-client contains mostly Py2 drop:
https://github.com/websocket-client/websocket-client/blob/master/ChangeLog

attrs contains Backward-incompatible Changes which doesn’t
seem to concern DuniterPy:
https://github.com/python-attrs/attrs/blob/main/CHANGELOG.rst

pyproject.toml

@@ -28,12 +28,12 @@ build-backend = "poetry.core.masonry.api"
 python = "^3.6.8"
 jsonschema = "^3.2.0"
 pypeg2 = "^2.15.2"
-attrs = "^20.2.0"
-base58 = "^2.0.0"
+attrs = "^21.2.0"
+base58 = "^2.1.0"
 libnacl = "^1.7.2"
 pyaes = "^1.6.1"
 graphql-core = "^3.1.2"
-websocket-client = "^0.57"
+websocket-client = "^1.1.0"
 mnemonic = "^0.19"
 
 [tool.poetry.dev-dependencies]