Add `accelerate` support for LongT5 models (#20341)
* ✨ add accelerate support for LongT5 models
Signed-off-by: peter szemraj <peterszemraj@gmail.com>
* fix `accelerate` tests
* Trigger CI test
Signed-off-by: peter szemraj <peterszemraj@gmail.com>
Co-authored-by: younesbelkada <younesbelkada@gmail.com>
