update generation config defaults

`early_stopping` prevents hallucinations when using beam search
`suppress_tokens` ensures the audio token will not be predicted.

generation_config.json

@@ -4,5 +4,7 @@
   "eos_token_id": 0,
   "pad_token_id": 0,
   "transformers_version": "4.52.0.dev0",
-  "use_cache": true
+  "use_cache": true,
+  "early_stopping": true,
+  "suppress_tokens": [49159]
 }