message: plugins/todo: replace usage of deprecated serializeEntityRef
diff: * limitations under the License.
  */
  -import { serializeEntityRef } from '@backstage/catalog-model';
  +import { stringifyEntityRef } from '@backstage/catalog-model';
  import { ResponseError } from '@backstage/errors';
  import { TodoApi, TodoListOptions, TodoListResult } from './types';
  import { DiscoveryApi, IdentityApi } from '@backstage/core-plugin-api';
  @@ -55,7 +55,7 @@ export class TodoClient implements TodoApi {
  const query = new URLSearchParams();
  if (entity) {
  - query.set('entity', serializeEntityRef(entity) as string);
  + query.set('entity', stringifyEntityRef(entity));
  }
  if (typeof offset === 'number') {
  query.set('offset', String(offset));
  