Making `safetensors` a core dependency.
Author: Narsil
Pull request: yes

# What does this PR do?


Making `safetensors` a core dependency.

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Fixes # (issue)


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## Who can review?

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Models:

- text models: @ArthurZucker and @younesbelkada
- vision models: @amyeroberts
- speech models: @sanchit-gandhi
- graph models: @clefourrier

Library:

- flax: @sanchit-gandhi
- generate: @gante
- pipelines: @Narsil
- tensorflow: @gante and @Rocketknight1
- tokenizers: @ArthurZucker
- trainer: @sgugger

Integrations:

- deepspeed: HF Trainer: @stas00, Accelerate: @pacman100
- ray/raytune: @richardliaw, @amogkam

Documentation: @sgugger, @stevhliu and @MKhalusova

HF projects:

- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Maintained examples (not research project or legacy):

- Flax: @sanchit-gandhi
- PyTorch: @sgugger
- TensorFlow: @Rocketknight1

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Comments:
_The documentation is not available anymore as the PR was closed or merged._

> If it is in the `install_requires` it doesn't need to be anywhere else.

`tokenizers` is in the `install_requires` too, yet in a bunch of other places (I merely copied it). Isn't `tokenizers`  a core dependency ? 

Yes it is. It was not added by me and way before I was asked to review PRs for Transformers ;-)

Linked blogpost : https://github.com/huggingface/blog/pull/1096

This means that weights are now always loaded in safetensors format but still saved in PyTorch format no? Think this is a good first step. Don't see a problem with having `safetensors` as a core dependency

> This means that weights are now always loaded in safetensors format but still saved in PyTorch format no? Think this is a good first step. Don't see a problem with having safetensors as a core dependency

Indeed. 

The next step will be saving in `safetensors` first. But we need to let time pass so that we can ensure a vast majority of users has `safetensors` so that users using a somewhat old transformers can  still load new models (finetuned versions of existing models in old versions)

Merging !