Update tests.yml

Author: xuanxu

.github/workflows/tests.yml

@@ -33,3 +33,5 @@ jobs:
     - name: Test against installed code
       run: pytest -v --cov-report=xml --cov=starmatrix
     - uses: codecov/codecov-action@v4
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}