New run_seq2seq script (#9605)
* New run_seq2seq script
* Add tests
* Mark as slow
* Update examples/seq2seq/run_seq2seq.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
* Update src/transformers/data/data_collator.py
Co-authored-by: Suraj Patil <surajp815@gmail.com>
* Update src/transformers/data/data_collator.py
Co-authored-by: Suraj Patil <surajp815@gmail.com>
* Address review comments
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Suraj Patil <surajp815@gmail.com>
