Added codestyle check and lint to the build action (#798)

* Applied `make format`

* Added format-check to makefile

* Added a "Check codestyle" step to the build action.

* Rerun `make format`

* Added a "lint" target to makefile

* Added lint step to the build action

* Added W503 to the list of ignored flake8 errors.

See https://www.flake8rules.com/rules/W503.html

.github/workflows/build.yml

@@ -20,6 +20,10 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install -r requirements.dev.txt
+    - name: Check codestyle
+      run: make format-check
+    - name: Lint
+      run: make lint
     - name: Test with pytest
       env:
         CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}