GitHub Action to run mypy on Python type hints

Author: cclauss

.github/workflows/mypy.yml

@@ -0,0 +1,12 @@
+name: mypy
+on: [pull_request, push]
+jobs:
+  mypy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - run: pip install mypy
+      - run: pip install -r requirements.txt
+      - run: mkdir --parents --verbose .mypy_cache
+      - run: mypy --ignore-missing-imports --install-types --non-interactive . || true