Added poetry integration.

Description:
* Fixed github actions;
* Removed requirements.txt;
* Fixed CONTRIBUTING.md;
* Fixed black and flake8.

Signed-off-by: Pavel <win10@list.ru>

.github/workflows/python-publish.yml

@@ -20,12 +20,13 @@ jobs:
         python-version: '3.x'
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade pip
-        pip install setuptools wheel twine
+        python -m pip install --upgrade poetry
+        poetry install --no-dev
+      env:
+        POETRY_VIRTUALENVS_CREATE: false
     - name: Build and publish
       env:
-        TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
-        TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
+        POETRY_HTTP_BASIC_PYPI_USERNAME: ${{ secrets.PYPI_USERNAME }}
+        POETRY_HTTP_BASIC_PYPI_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
       run: |
-        python setup.py sdist bdist_wheel
-        twine upload dist/*
+        poetry publish --build