fix: skip JSON fallback when web_search tool is present

When web_search tools are used, falling back to JSON mode causes
an error because OpenAI doesn't support JSON mode with web search.

This fix detects web_search tools in lm_kwargs and skips the JSON
fallback, raising the original error instead for better debugging.

Fixes #8958

Author: bhaskargurram-ai

dspy/adapters/chat_adapter.py

@@ -44,6 +44,13 @@ def __call__(
                 # On context window exceeded error or already using JSONAdapter, we don't want to retry with a different
                 # adapter.
                 raise e
+            
+            tools = lm_kwargs.get('tools', [])
+            has_web_search = any(tool.get('type') == 'web_search' for tool in tools if isinstance(tool, dict))
+        
+            if has_web_search:
+                # Don't fall back to JSON mode with web search - raise the original error
+                raise e
             return JSONAdapter()(lm, lm_kwargs, signature, demos, inputs)
 
     async def acall(