fixed teh coderabbit mentioned issue

Author: Abishek-Newar

openfga_sdk/client/client.py

@@ -120,8 +120,6 @@ def options_to_kwargs(
             kwargs["_headers"] = options["headers"]
         if options.get("retry_params"):
             kwargs["_retry_params"] = options["retry_params"]
-        if options.get("async_req") is not None:
-            kwargs["async_req"] = options["async_req"]
     return kwargs