Use upload token for Codecov coverage reports.

Author: john-hen

.github/workflows/coverage.yml

@@ -29,6 +29,7 @@ jobs:
         run:  pytest --cov --cov-report xml
 
       - name: Upload coverage report.
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v5
         with:
+          token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true