pin: torchaudio to >=2.7.0,<2.9

[deependujha]

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

From Torchaudio >=2.9, Most APIs marked as pytorch/audio#3902 (comment) are now removed. This results in CI tests failing for litdata-torchaudio dataset optimization. check failing tests here.

We can either bump torchaudio to older release as a quick fix, or for latest torchaudio support, we need to update existing api calls, and install ffmpeg followed by torchcodec to pass tests.

As a quick fix, this PR pins torchaudio to an older compatible release to restore CI stability.

If we’d prefer to support the latest Torchaudio release instead, I can update this PR to include the necessary API adjustments and add ffmpeg, torchcodec, and torchaudio installation steps in the CI workflow.

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in GitHub issues there's a high chance it will not be merged.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80%. Comparing base (e69fdd0) to head (74879f9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #738   +/-   ##
===================================
  Coverage    80%    80%           
===================================
  Files        52     52           
  Lines      7330   7330           
===================================
  Hits       5868   5868           
  Misses     1462   1462           

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