Fix compat with HF Transformers `model.save_pretrained()`

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

@@ -1,15 +1,15 @@
-{
-  "max_new_tokens": 1000,
-  "do_sample": false,
-  "use_cache": true,
-  "temperature": 0.0,
-  "top_k": 5,
-  "top_p": 0.85,
-  "repetition_penalty": 1.05,
-  "pad_token_id": 3,
-  "bos_token_id": 1,
-  "eos_token_id": 2,
-  "user_token_id": 4,
-  "bot_token_id": 5,
-  "start_token_id": 1
-}
+{
+  "max_new_tokens": 1000,
+  "do_sample": true,
+  "use_cache": true,
+  "temperature": 0.0,
+  "top_k": 5,
+  "top_p": 0.85,
+  "repetition_penalty": 1.05,
+  "pad_token_id": 3,
+  "bos_token_id": 1,
+  "eos_token_id": 2,
+  "user_token_id": 4,
+  "bot_token_id": 5,
+  "start_token_id": 1
+}