fix typo in web_research.py (#10076)

fix spelling

libs/langchain/langchain/retrievers/web_research.py

@@ -150,7 +150,7 @@ class WebResearchRetriever(BaseRetriever):
         return query.strip()
 
     def search_tool(self, query: str, num_search_results: int = 1) -> List[dict]:
-        """Returns num_serch_results pages per Google search."""
+        """Returns num_search_results pages per Google search."""
         query_clean = self.clean_search_query(query)
         result = self.search.results(query_clean, num_search_results)
         return result