Update _name to "arcee-ai/SuperNova-Medius"

When trying to serve this model with vllm, model loaded fine, but I got error:

```
{"object":"error","message":"The model `arcee-ai/SuperNova-Medius` does not exist.","type":"NotFoundError","param":null,"code":404}++ curl --write-out '%{http_code}' --silent --output /dev/null -H 'Content-Type: application/json' -d '{
"model": "arcee-ai/SuperNova-Medius",
"messages": [{"role": "user", "content": "Say this is a test!"}],
"max_tokens": 7,
"temperature": 0
}' http://localhost:8080/v1/chat/completions
```

This hopefully fixes that.

config.json

@@ -1,5 +1,5 @@
 {
-  "_name_or_path": "Qwen/Qwen2.5-14B",
+  "_name_or_path": "arcee-ai/SuperNova-Medius",
   "architectures": [
     "Qwen2ForCausalLM"
   ],