add pep8 workflow

.gitea/workflows/python-pep8.yaml

@@ -0,0 +1,18 @@
+python-pep8:
+  name: Python formatting PEP8
+  runs-on: ubuntu-latest
+
+  steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+    - uses: actions/setup-python@v2
+      with:
+        python-version: 3.9
+
+    - name: Install dependencies
+      run: |
+        pip install flake8
+
+    - name: Run checking
+      run: |
+        flake8 --extend-exclude bin,lib .