ref(test): remove torchaudio dependency and update audio processing to just use soundfile

[bhimrazy]

What does this PR do?

Removes torchaudio dependency (to perform minimal tasks in tests) and update audio processing to use soundfile

Follow up to #738

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80%. Comparing base (359bbf1) to head (56f0216).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #739   +/-   ##
===================================
- Coverage    80%    80%   -0%     
===================================
  Files        52     52           
  Lines      7330   7329    -1     
===================================
- Hits       5869   5867    -2     
- Misses     1461   1462    +1     

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