Add missing comma in game_port argument

A missing comma was discovered and corrected in the game_port argument on the study_server.py file. This could potentially prevent syntax errors and bugs that might result from incomplete statements and ensure smoother execution of the function.

cooperative_cuisine/study_server.py

@@ -450,7 +450,7 @@ if __name__ == "__main__":
         args.study_url,
         args.study_port,
         game_host=args.game_url,
-        game_port=args.game_port
+        game_port=args.game_port,
         manager_ids=args.manager_ids,
         study_config_path=args.study_config,
     )