[`Falcon`] Remove SDPA for falcon to support earlier versions of PyTorch (< 2.0) (#25947)
* remove SDPA for falcon
* revert previous behaviour and add warning
* nit
* Update src/transformers/models/falcon/modeling_falcon.py
Co-authored-by: Matt <Rocketknight1@users.noreply.github.com>
* Update src/transformers/models/falcon/modeling_falcon.py
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Co-authored-by: Matt <Rocketknight1@users.noreply.github.com>
Co-authored-by: Lysandre Debut <hi@lysand.re>