catching also PL deprecation warnigs

[Borda]

🚀 Feature

if we want to be progressive incompatibility we shall also report on deprecation warnings and eventually treat them as failer...
as an alternative, we can give a user option to set it as strict 🤔

Pitch

Compatibility for the future

Alternatives

pass pytest argument -W error::DeprecationWarning in
https://github.com/PyTorchLightning/ecosystem-ci/blob/c544b7bc10fbef6f6b498805dd08837eb1ba96a2/actions/_config.yaml#L54

Additional context

https://docs.pytest.org/en/latest/how-to/capture-warnings.html#controlling-warnings

[rohitgr7]

to just catch the deprecation warnings as an error, we need to somehow catch LightningDeprecationWarning from pytorch-lightning.

Just like:
https://github.com/PyTorchLightning/pytorch-lightning/blob/00d1758bac69d55e934e43f3961ba328a2b8951e/setup.cfg#L27-L29

but here pytorch-lightning is an external package, so we need to figure out how we can do that.