Update codecov/codecov-action action to v4 (#4)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/test.yml

@@ -24,4 +24,4 @@ jobs:
         run: bun run test:coverage
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4