Make httpx's sync transport configurable

Author: leventov

litellm/llms/custom_httpx/http_handler.py

@@ -915,7 +915,7 @@ def _create_sync_transport(self) -> Optional[HTTPTransport]:
         if litellm.force_ipv4:
             return HTTPTransport(local_address="0.0.0.0")
         else:
-            return None
+            return getattr(litellm, 'sync_transport', None)
 
 
 def get_async_httpx_client(