Add python lint to github actions

.github/workflows/ci.yaml

@@ -62,4 +62,18 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: clippy
-          args: --all -- -Dwarnings
+          args: --all -- -Dwarnings
+
+  lint:
+    name: Lint Python code with flake8
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - uses: actions/setup-python@v1
+        with:
+          python-version: 3.6
+      - name: install flake8
+        run: python -m pip install flake8
+      - name: run lint
+        run: flake8 . --count --exclude=./.*,./Lib,./vm/Lib  --select=E9,F63,F7,F82 --show-source --statistics
+