Add token_type_ids to prepare_inputs_for_generation for gpt/gpt2
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Fixes #{issue number}

Maybe related to https://github.com/huggingface/transformers/pull/6601 and https://github.com/huggingface/transformers/pull/7552<|||||>Yes seems to be related to both. https://github.com/huggingface/transformers/pull/7355 doesn't seem to have token_type_ids passed in though, but if those PRs get merged in I'll close mine<|||||>We have the same problem here as explained in https://github.com/huggingface/transformers/pull/6601#issuecomment-708029212. <|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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