[misc] upgrade format to py39 (#7256)

src/llamafactory/train/pt/trainer.py

@@ -31,9 +31,7 @@ if TYPE_CHECKING:
 
 
 class CustomTrainer(Trainer):
-    r"""
-    Inherits Trainer for custom optimizer.
-    """
+    r"""Inherit Trainer for custom optimizer."""
 
     def __init__(
         self, finetuning_args: "FinetuningArguments", processor: Optional["ProcessorMixin"], **kwargs

src/llamafactory/train/pt/workflow.py

@@ -16,7 +16,7 @@
 # limitations under the License.
 
 import math
-from typing import TYPE_CHECKING, List, Optional
+from typing import TYPE_CHECKING, Optional
 
 from transformers import DataCollatorForLanguageModeling
 
@@ -38,7 +38,7 @@ def run_pt(
     data_args: "DataArguments",
     training_args: "Seq2SeqTrainingArguments",
     finetuning_args: "FinetuningArguments",
-    callbacks: Optional[List["TrainerCallback"]] = None,
+    callbacks: Optional[list["TrainerCallback"]] = None,
 ):
     tokenizer_module = load_tokenizer(model_args)
     tokenizer = tokenizer_module["tokenizer"]