ci: rollback codecov action to v3.

Author: ghosind

.github/workflows/coverage.yaml

@@ -18,6 +18,6 @@ jobs:
       run: go test -v ./... -coverprofile=coverage.out
 
     - name: Upload coverage report
-      uses: codecov/codecov-action@v4
+      uses: codecov/codecov-action@v3
       with:
         token: ${{ secrets.CODECOV_TOKEN }}