New learning rate schedulers

[rubenjr0]

Pull Request Template

Checklist

• Confirmed that run-checks all script has been executed.
• Made sure the book is up to date with changes in this PR.

Related Issues/PRs

#1198

Changes

• Implementation of an Exponential learning rate scheduler
• Implementation of a Cosine Annealing learning rate scheduler with cold restarts

Testing

New unit tests following the same structure as the previously implemented schedulers' tests have been implemented.

[rubenjr0]

The run-checks all script sometimes fails because of #1478

[codecov]

Codecov Report

Attention: Patch coverage is 78.39506% with 35 lines in your changes are missing coverage. Please review.

Project coverage is 85.76%. Comparing base (41d01b8) to head (507f948).

Files	Patch %	Lines
crates/burn-core/src/lr_scheduler/cosine.rs	76.00%	24 Missing ⚠️
crates/burn-core/src/lr_scheduler/exponential.rs	82.25%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1481      +/-   ##
==========================================
- Coverage   85.77%   85.76%   -0.02%     
==========================================
  Files         649      651       +2     
  Lines       72416    72578     +162     
==========================================
+ Hits        62117    62244     +127     
- Misses      10299    10334      +35     

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[antimora]

Thank you for these additions. Looks great to me.

Waiting for one more reviewer.

[laggui]

LGTM! Thanks for the contribution 🙂