refac: modernize type annotations (PEP 604 / PEP 585)

backend/open_webui/retrieval/web/serper.py

@@ -8,6 +8,7 @@ from open_webui.retrieval.web.main import SearchResult, get_filtered_results
 
 log = logging.getLogger(__name__)
 
+
 def search_serper(api_key: str, query: str, count: int, filter_list: list[str | None] = None) -> list[SearchResult]:
     """Search using serper.dev's API and return the results as a list of SearchResult objects.