FIX compat with HF transformers save

Latest transformers (4.49.0), likely earlier versions too, will now validate the generation config file and since `top_k` and `temperature` non-default values are set, `do_sample` must be set to `True` or eles this configuration is self-conflicting.

generation_config.json

@@ -1,6 +1,6 @@
 {
   "max_new_tokens": 1000,
-  "do_sample": false,
+  "do_sample": true,
   "use_cache": true,
   "temperature": 0.3,
   "top_k": 5,