Update default model name

trainer.py

@@ -83,8 +83,8 @@ class Trainer:
         resolution = int(resolution_s)
 
         if not output_model_name:
-            output_model_name = datetime.datetime.now().strftime(
-                '%Y-%m-%d-%H-%M-%S')
+            timestamp = datetime.datetime.now().strftime('%Y-%m-%d-%H-%M-%S')
+            output_model_name = f'lora-dreambooth-{timestamp}'
         output_model_name = slugify.slugify(output_model_name)
 
         repo_dir = pathlib.Path(__file__).parent