ci: add ty installation to test workflow

ty is installed via uv tool, not as a pip package.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Mazyod

.github/workflows/python-tests.yml

@@ -42,6 +42,9 @@ jobs:
     - name: Add npm global bin to PATH
       run: echo "$HOME/.npm-global/bin" >> $GITHUB_PATH
 
+    - name: Install ty (Astral's type checker)
+      run: uv tool install ty
+
     # - name: Lint with flake8
     #   run: |
     #     # stop the build if there are Python syntax errors or undefined names