ci(actions): bump codecov/codecov-action from v6 to v7

- Update codecov/codecov-action GitHub Action from v6 to v7

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: appleboy

.github/workflows/testing.yml

@@ -53,7 +53,7 @@ jobs:
           go test -v -covermode=atomic -coverprofile=coverage.out ./...
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v6
+        uses: codecov/codecov-action@v7
 
   vulnerability-scanning:
     runs-on: ubuntu-latest