Update codecov/codecov-action action to v4.6.0

Author: renovate[bot]

.github/workflows/flutter.yml

@@ -40,7 +40,7 @@ jobs:
         with:
           name: failures
           path: "**/failures/"
-      - uses: codecov/codecov-action@e28ff129e5465c2c0dcc6f003fc735cb6ae0c673 # v4.5.0
+      - uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4.6.0
         with:
           fail_ci_if_error: true
           token: ${{ secrets.CODECOV_TOKEN }}