Revert "Unpin protobuf in docker file (for daily CI)"
Reverts huggingface/transformers#24761

ONNX unfortunately doesn't support using protobuf v4, and our daily CI have many ONNX tests broken after #24761.

See [failing jobs](https://github.com/huggingface/transformers/actions/runs/5526985620)


Merge directly so we can have a better CI report in the next run.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_24800). All of your documentation changes will be reflected on that endpoint.<|||||>@sgugger Just to let you know I revert a merged PR #24761: There is no super easy way to move (all) the ONNX-related tests to another job. We get stuck with protobuf v3 on daily CI.<|||||>Shouldn't all the ONNX tests be done on the optimum side now?<|||||>Yes. I know you once mentioned to me that we will ignore failing ONNX tests (`tests/onnx`) - but I don't know if you are OK for us to completely remove it (as all of them are failing with protobuf v4).

But the story is longer: we have tests  like `TFGPT2ModelTest::test_onnx_runtime_optimize` that are defined in individual model test file, and not in `tests/onnx`. Of course, I am happy if the Optimum can take care of this on their side.<|||||>cc @michaelbenayoun Can you confirm it's okay for us to remove all ONNX tests? They all test the deprecated way of using ONNX as far as I know.<|||||>The issue here is that these tests rely on a pretty old release (v1.12.0) of `onnx`: https://github.com/huggingface/transformers/actions/runs/5526985620/jobs/10082374086#step:8:159

The last release should be compatible with `protobuf` v4.

Other than this, it sounds good to me to remove all ONNX tests in Transformers :+1: 
@michaelbenayoun and @fxmarty will know better though.<|||||>@regisss Thank you for the heads up ❤️  - but yes it would be great if we can delegate the ONNX testing to Optimum CI.<|||||>@ydshieh @sgugger Yes I believe it is fine to remove the ONNX tests from transformers, as the export in Optimum is now mature, extended and well tested!<|||||>Thanks!