CI: strict mypy check in github actions

mypy_files.txt is a list of files that will fail the CI if mypy finds errors in them

.github/workflows/strict-type-check.yml

@@ -0,0 +1,27 @@
+name: type check
+
+on:
+  pull_request:
+    paths:
+      - "**.py"
+  push:
+    paths:
+      - "**.py"
+
+jobs:
+  mypy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: "Install dependencies"
+        run: |
+          python -m pip install --upgrade pip mypy
+          python ModuleUpdate.py --append "WebHostLib/requirements.txt" --force --yes
+
+      - name: "mypy: strict check on specific files"
+        run: .github/mypy_check.sh