Updated Codecov GitHub action (#1222)

Author: sliverc

.github/workflows/tests.yml

@@ -30,8 +30,9 @@ jobs:
       - name: Run tox targets for ${{ matrix.python-version }}
         run: tox run -f py$(echo ${{ matrix.python-version }} | tr -d .)
       - name: Upload coverage report
-        uses: codecov/codecov-action@v2
+        uses: codecov/codecov-action@v4
         with:
+          token: ${{ secrets.CODECOV_TOKEN }}
           env_vars: PYTHON
   check:
     name: Run check