Update serpapi.py (#4947)

Added link option in  _process_response

<!--
In _process_respons "snippet" provided non working links for the case
that "links" had the correct answer. Thus added an elif statement before
snippet
-->

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Fixes # (issue)
In _process_response link provided correct answers while the snippet
reply provided non working links

@vowelparrot 
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---------

Co-authored-by: Dev 2049 <dev.dev2049@gmail.com>

langchain/utilities/serpapi.py

@@ -150,6 +150,8 @@ class SerpAPIWrapper(BaseModel):
             toret = res["knowledge_graph"]["description"]
         elif "snippet" in res["organic_results"][0].keys():
             toret = res["organic_results"][0]["snippet"]
+        elif "link" in res["organic_results"][0].keys():
+            toret = res["organic_results"][0]["link"]
 
         else:
             toret = "No good search result found"