fix(modeling_attn_mask_utils): remove FutureWarning from logger.warning_once()

[imstevenpmwork]

What does this PR do?

This PR fixes a TypeError: not all arguments converted during string formatting caused by incorrectly passing FutureWarning as a second argument to logger.warning_once() in this file, introduced in #42848. Because Python's logging module expects string formatting arguments (like %s) rather than warning categories, passing FutureWarning without a placeholder triggered a crash when the warning evaluated.

I prioritized the use of logger.warning_once() instead of warnings.warn(msg, FutureWarning) to align with the logging patterns in similar transformers modeling_ utils files. -> This was later changed to prefer warnings for sake of preserving the FutureWarning: #44307 (comment)

I didn't test this locally, but here's a small snippet for reproduction:

>>> import logging
>>> DEPRECATION_MESSAGE = "test"
>>> logging.warning(DEPRECATION_MESSAGE)
WARNING:root:test
>>> logging.warning(DEPRECATION_MESSAGE,FutureWarning)
--- Logging error ---
Traceback (most recent call last):
  File "/Users/steven.palma/miniforge3/lib/python3.12/logging/__init__.py", line 1160, in emit
    msg = self.format(record)
          ^^^^^^^^^^^^^^^^^^^
  File "/Users/steven.palma/miniforge3/lib/python3.12/logging/__init__.py", line 999, in format
    return fmt.format(record)
           ^^^^^^^^^^^^^^^^^^
  File "/Users/steven.palma/miniforge3/lib/python3.12/logging/__init__.py", line 703, in format
    record.message = record.getMessage()
                     ^^^^^^^^^^^^^^^^^^^
  File "/Users/steven.palma/miniforge3/lib/python3.12/logging/__init__.py", line 392, in getMessage
    msg = msg % self.args
          ~~~~^~~~~~~~~~~
TypeError: not all arguments converted during string formatting
Call stack:
  File "<stdin>", line 1, in <module>
Message: 'test'
Arguments: (<class 'FutureWarning'>,)
>>>

Here's an example of this happening in downstream libraries: https://github.com/huggingface/lerobot/actions/runs/22455225460/job/65035766998

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Who can review?

• Anyone in the community is free to review the PR once the tests have passed.
• @vasqu @ArthurZucker

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[vasqu]

Oops, that's on me #42848 😬

Let's use warnings.warn instead, would like to keep the future warning type in this case - we can safely remove the logger in this file then iirc.

[imstevenpmwork]

Addressed in commit: 15b3afa

[vasqu]

Perfect, thank you