Fix python-unittest.yaml (#950)

Author: yikaiMeta

.github/workflows/python-unittests.yaml

@@ -39,7 +39,7 @@ jobs:
       - name: Run tests
         run: pytest --cov=./ --cov-report=xml
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           env_vars: OS,PYTHON