Feature/lightning 2.1

[belerico]

Summary

In this PR we have upgraded the lightning to the 2.1 version in order prepare to the merge to PyTorch 2.1. In particular:

• the fabric object is instantiated through hydra.utils.instantiate method; this let a user to modify the fabric object from the config, specifying custom accelerators, callbacks, strategies, devices and precision objects
• cli.py now checks for configs. In particular we check that decoupled algorithms run only with DDP strategies
• torchmetrics has been updated to the master version

Type of Change

Please select the one relevant option below:

• New feature (non-breaking change that adds functionality)

Checklist

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• I have tested my changes locally and they work as expected. (Please describe the tests you performed.)
• I have added unit tests for my changes, or updated existing tests if necessary.
• I have updated the documentation, if applicable.
• I have installed pre-commit and run locally for my code changes.

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