fix: disable whisper, faster_whisper, and hugging_face transcriptions in linux build

[chidiwilliams]

This disables Whisper, Faster Whisper and Hugging Face transcriptions in Linux build to avoid Snap distribution errors.

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (5456774) 77.74% compared to head (8c0abf2) 77.69%.

Files	Patch %	Lines
buzz/model_loader.py	92.30%	2 Missing ⚠️
buzz/recording_transcriber.py	80.00%	2 Missing ⚠️
buzz/whisper_audio.py	85.71%	2 Missing ⚠️
buzz/transcriber.py	90.90%	1 Missing ⚠️
...ts/preferences_dialog/models_preferences_widget.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #659      +/-   ##
==========================================
- Coverage   77.74%   77.69%   -0.05%     
==========================================
  Files          62       63       +1     
  Lines        3248     3291      +43     
==========================================
+ Hits         2525     2557      +32     
- Misses        723      734      +11     

Flag	Coverage Δ
Linux	71.77% <76.82%> (-3.85%)	⬇️
Windows	?
macOS	76.45% <87.80%> (+0.21%)	⬆️

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