Pvt model
# Add PVT(Pyramid Vision Transformer)


Partially fixes: [issue](https://github.com/huggingface/transformers/issues/17596), [Closed PR](https://github.com/huggingface/transformers/pull/22445)

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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      Pull Request section?
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      to it if that's the case.
- [x] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [x] Did you write any new necessary tests?


## Who can review?

@amyeroberts


From previous PR:

> PvtBlock which contains a PvtPatchEmbeddings layer and the subsequent PvtLayer layers. 
PvtLayer has depth, while PvtPatchEmbeddings only at the beginning of the each encoder block and it would be trailed along the whole depth without using or it would require extra logic to make it None and also would require to trail height and width.

_The documentation is not available anymore as the PR was closed or merged._<|||||>@Xrenya Thanks again for adding and iterating. Merging now :) 