Update brave.py to use the correct field

fixing issues caused by incorrect field names.

backend/open_webui/retrieval/web/brave.py

@@ -36,7 +36,7 @@ def search_brave(
 
     return [
         SearchResult(
-            link=result["url"], title=result.get("title"), snippet=result.get("snippet")
+            link=result["url"], title=result.get("title"), snippet=result.get("description")
         )
         for result in results[:count]
     ]