Use client_metadata to determine if 2LO should be used

Author: LucaButBoring

src/mcp/client/auth.py

@@ -320,10 +320,7 @@ async def _handle_registration_response(self, response: httpx.Response) -> None:
 
     async def _perform_authorization(self) -> httpx.Request:
         """Perform the authorization flow."""
-        if not self.context.client_info:
-            raise OAuthFlowError("No client info available for authorization")
-
-        if "client_credentials" in self.context.client_info.grant_types:
+        if "client_credentials" in self.context.client_metadata.grant_types:
             token_request = await self._exchange_token_client_credentials()
             return token_request
         else: