Add mypy check to CI

Author: jmattsson

.github/workflows/checks.yml

@@ -0,0 +1,27 @@
+---
+name: Code checks
+
+"on":
+  push:
+
+  workflow_dispatch:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v5
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: '3.12'
+
+      - name: Install dependencies
+        run: |
+          pip install mypy
+
+      - name: Run mypy checks
+        run: |
+          python3 -m mypy --show-error-codes --show-column-numbers src