Run mypy in GHA

.github/workflows/build-and-release.yaml

@@ -37,6 +37,20 @@ jobs:
       - name: Ruff
         run: ruff check --no-cache --output-format github .
 
+      - name: Install production requirements (for Mypy)
+        run: |
+          # Mypy needs production packages for typechecking
+          sudo apt-get update
+          sudo apt-get install -y \
+            python3-dev \
+            libsnappy-dev \
+            libxml2-dev \
+            libxslt1-dev
+          pip install --no-deps -r requirements/requirements-prod.txt
+
+      - name: Mypy
+        run: mypy
+
   check-compiled-requirements:
     runs-on: ubuntu-24.04
     if: ${{ !contains(github.event.head_commit.message, '#notests') }}