[setup.py] note on how to get to transformers exact dependencies from shell

[stas00]

As a follow up to #9550, this PR adds a few handy one liners to quickly access the correct dependency versions from shell.

e.g if you want to install deps for a group of packages we control and with their correct versions, you just need to run:

pip install -U $(python -c 'import sys; from transformers.dependency_versions_table import deps; \
print(" ".join([deps[x] for x in sys.argv[1:]]))' numpy filelock protobuf requests tqdm regex \
sentencepiece sacremoses tokenizers packaging importlib_metadata)

that was one option for torchhub, but since it didn't have transformers installed it didn't work and a different solution was provided #9552

@sgugger, @LysandreJik

[sgugger]

Thanks for documenting this!

[LysandreJik]

Cool, thanks @stas00!