Adding support for OpenAI GPT-5 model; Models only support hardcoded...

Adding support for OpenAI GPT-5 model; Models only support hardcoded tempeature=1 and stop=None (#3247)

lm_eval/models/openai_completions.py

@@ -289,7 +289,7 @@ class OpenAIChatCompletion(LocalChatCompletion):
             "seed": seed,
             **gen_kwargs,
         }
-        if "o1" in self.model:
+        if "o1" in self.model or "5" in self.model:
             output.pop("stop")
             output["temperature"] = 1
         elif "o3" in self.model: