Fix a mis-aligned else that causes a crash

[mkserge]

Fixes an issue introduced in the commit 984ca2dc where the else is misaligned causing the following crash when running data validation tool.

Traceback (most recent call last):
  File "<frozen runpy>", line 189, in _run_module_as_main
  File "<frozen runpy>", line 159, in _get_module_details
  File "<frozen importlib._bootstrap_external>", line 1074, in get_code
  File "<frozen importlib._bootstrap_external>", line 1004, in source_to_code
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/ec2-user/workspace/mistral/mistral-finetune/utils/validate_data.py", line 113
    else:
TabError: inconsistent use of tabs and spaces in indentation