Install `tensorflow_probability` for TF pipeline CI
# What does this PR do?

So tests like `TQAPipelineTests.test_integration_sqa_tf` or `TQAPipelineTests.test_slow_tokenizer_sqa_tf` could run.
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20586). All of your documentation changes will be reflected on that endpoint.