Correct tests workflow syntax

Author: Perseudonymous

.github/workflows/tests.yml

@@ -11,7 +11,8 @@ jobs:
       - uses: actions/checkout@v4
       - name: Set up Python
         uses: actions/setup-python@v5
-        python-version: ${{ matrix.python-version }}
+        with:
+          python-version: ${{ matrix.python-version }}
       - name: Install requirements
         run: pip install -r requirements-dev.txt
       - name: Run tests