Update codecov github action to v4 (#92)

Author: Muscaw

.github/workflows/package.yml

@@ -32,7 +32,7 @@ jobs:
           poetry run pip install tox-gh-actions
           poetry run tox -elint
       - name: Upload code coverage
-        uses: codecov/codecov-action@v2
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           file: ./coverage.xml