Add requirements.txt instead of setup.cfg

.github/workflows/python-tests.yml

@@ -18,8 +18,8 @@ jobs:
           architecture: x64
       - name: Install dependencies
         run: |
-          python -m pip install --upgrade pip setuptools
-          pip install --progress-bar off .[lint]
+          python -m pip install --progress-bar off --upgrade pip setuptools
+          pip install --progress-bar off flake8 black isort mypy
       - run: flake8 . --show-source
       - run: black --check --diff .
       - run: isort --check --diff .