Remove agent if without serpapi

1. when the agent added, the performance of docGPT always not good
2. therefore, if the user just need ask question about document, and no need use serpapi, we'll use docGPT only

Author: Lin-jun-xiang

docGPT/__init__.py

@@ -44,14 +44,16 @@ def create_doc_gpt(docs):
             if SerpAPI.is_valid():
                 search_tool = agent_.get_searp_chain
 
-            tools = [
-                docGPT_tool,
-                search_tool,
-                # llm_tool, # This will cause agent confuse
-                calculate_tool
-            ]
-            agent_.initialize(tools)
-            return agent_ if agent_ is not None else None
+                tools = [
+                    docGPT_tool,
+                    search_tool,
+                    # llm_tool, # This will cause agent confuse
+                    calculate_tool
+                ]
+                agent_.initialize(tools)
+                return agent_ if agent_ is not None else None
+            else:
+                return docGPT
         else:
             # Use gpt4free llm model without agent
             llm_model = GPT4Free(