Make beta tc loss more stable using torch.logsumexp

[meffmadd]

The code is from https://github.com/YannDubs/disentangling-vae
The PyTorch implementation uses a more stable implementation than just chaining .log().sum.exp()

[meffmadd]

Will also look into using torch.Normal for _betatc_compute_gaussian_log_density.

[codecov]

Codecov Report

Base: 70.04% // Head: 70.04% // No change to project coverage 👍

Coverage data is based on head (1446fd8) compared to base (de159f2).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #41   +/-   ##
=======================================
  Coverage   70.04%   70.04%           
=======================================
  Files         135      135           
  Lines        7538     7538           
=======================================
  Hits         5280     5280           
  Misses       2258     2258           

Impacted Files	Coverage Δ
disent/frameworks/vae/_unsupervised__betatcvae.py	100.00% <100.00%> (ø)

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[nmichlo]

Sorry, for the delay getting back to you about this PR.

Good catch! Thank you so much for this contribution!

EDIT: I notice the old contributions are still part of the history, if there is anything in future it might be easier to start the commits from the main branch after synchronizing with upstream changes 😁