add flake8 to CI, skip remaining 4 flake8 issues (will be addressed later)

.github/workflows/flake8.yml

@@ -0,0 +1,26 @@
+name: flake8
+
+on: [push, pull_request]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.9"]
+        poetry-version: ["1.3.1"]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Set up Poetry ${{ matrix.poetry-version }}
+        uses: abatilo/actions-poetry@v2
+        with:
+          poetry-version: ${{ matrix.poetry-version }}
+      - name: Install dependencies
+        run: |
+          poetry install
+      - name: Run tests
+        run: make flake8