chore(deps): update codecov/codecov-action action to v4 (#689)

Author: renovate[bot]

Diff for: .github/workflows/tests.yaml

@@ -59,7 +59,7 @@ jobs:
         run: |
           pytest --cov=MySQLdb tests
 
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
 
   django-test:
     name: "Run Django LTS test suite"