Add flake8 github action with review dog

Review dog is an incredible project that makes linting and formatting
review a breeze by commenting inline what is wrong in a pull request.
This makes the review process easier for the maintainer and also
provides a clearer feedback to the contributor

.github/workflows/flake8.yml

@@ -0,0 +1,20 @@
+name: flake8
+
+on: pull_request
+
+jobs:
+    flake8-lint:
+        runs-on: ubuntu-latest
+        name: Lint
+        steps:
+            - name: Check out source repository
+              uses: actions/checkout@v2
+            - name: Set up Python environment
+              uses: actions/setup-python@v2
+              with:
+                  python-version: "3.9"
+            - name: flake8 Lint
+              uses: reviewdog/action-flake8@v3
+              with:
+                  github_token: ${{ secrets.GITHUB_TOKEN }}
+                  reporter: github-pr-review

tox.ini

@@ -6,11 +6,4 @@ setenv =
     PYTHONPATH = {toxinidir}:{toxinidir}/pipreqs
 commands = python setup.py test
 deps =
-    -r{toxinidir}/requirements.txt
-
-[testenv:flake8]
-basepython = python3.9
-commands = flake8 pipreqs
-deps =
-    -r{toxinidir}/requirements.txt
-    flake8
+    -r{toxinidir}/requirements.txt