fix: get mlflow version from mlflow-skinny

[clumsy]

What does this PR do?

mlflow module can be provided by either mlflow or mlflow-skinny packages. The latter is a more lightweight option.

After a recent change the usages of mlflow-skinny are broken for transformers see this discussion:

if packaging.version.parse(importlib.metadata.version("mlflow")) >= packaging.version.parse("2.8.0"):
  File "/opt/conda/lib/python3.9/importlib/metadata.py", line 569, in version
return distribution(distribution_name).version
  File "/opt/conda/lib/python3.9/importlib/metadata.py", line 542, in distribution
return Distribution.from_name(distribution_name)
  File "/opt/conda/lib/python3.9/importlib/metadata.py", line 196, in from_name
raise PackageNotFoundError(name)
importlib.metadata.PackageNotFoundError: mlflow

Fun fact: importlib.util.find_spec("mlflow") is not None check in is_mlflow_available actually passes for mlflow-skinny.

Fixes #29195

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[cchen-dialpad]

Thanks for fixing! Maybe need another review from HuggingFace, but otherwise LGTM

[ArthurZucker]

Makes sense! Kudos for the prompt fix and the catch!

[HuggingFaceDocBuilderDev]

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