[ENH] early return for deep_equals in case of object identity

[CloseChoice]

This fixes the following problem

    from pytorch_forecasting.metrics.quantile import QuantileLoss
    import numpy as np

    a = QuantileLoss(quantiles=[0.1, 0.2])
    assert deep_equals(a, a)  # Fails

this fails since the QuantileLoss overwrites __eq__ and __ne__. I simulate this in a test that fails on main as well, in order to not introduce another heavy dependency.

Reference Issues/PRs

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• I've reviewed the project documentation on contributing
• I've added myself to the list of contributors.
• The PR title starts with either [ENH], [CI/CD], [MNT], [DOC], or [BUG] indicating whether
  the PR topic is related to enhancement, CI/CD, maintenance, documentation, or a bug.

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• Unit tests have been added covering code functionality
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.12%. Comparing base (306958d) to head (2b8b80b).
⚠️ Report is 213 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #568      +/-   ##
==========================================
- Coverage   85.07%   84.12%   -0.95%     
==========================================
  Files          45       52       +7     
  Lines        3015     3963     +948     
==========================================
+ Hits         2565     3334     +769     
- Misses        450      629     +179     

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[fkiraly]

Good suggestion.