ci: extend ruff lint to tests/ directory

Applies the change from PR #14 directly since it conflicts with main.

Author: Coding-Dev-Tools

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
           pip install -e ".[dev]"
 
       - name: Lint with ruff
-        run: pip install ruff && ruff check src/ --target-version py310
+        run: pip install ruff && ruff check src/ tests/ --target-version py310
 
       - name: Run tests
         run: |