[CI] Deprecate Python3.7 and invalidate cache weekly

[Wauplin]

This PR is only a suggestion. Realized while working on https://github.com/huggingface/setfit/pull/505 that SetFit is tested on Python3.7 which is deprecated since June 2023 and not supported anymore by transformers/huggingface_hub/datasets.

What this PR do:

• do not test on Python3.7 anymore
• ~test on Python3.11 instead~. EDIT: test on Python 3.11 are failing due to "openvino==2022.3.0" being explicitly pinned so I remove support for 3.11. Might be worth checking this and adding it in a future PR.
• update READMEs and adapt code to remove Python3.7 support
• (unrelated) the test CI uses some cache to avoid redownloading all dependencies for each run. However it's usually good to invalidate this cache from time to time to avoid missing breaking changes from external dependencies. In this PR I suggest to invalidate the cache every week.

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[Wauplin]

Looks like CI is failing with 3 different errors:

• 2 in tests/span/test_model_card.py::test_model_card where model card is not exactly as expected. Should be fixed by https://github.com/huggingface/setfit/pull/505/commits/3649f36d88f5ef294a1ea3b1ec935436833cb0df (in the other PR https://github.com/huggingface/setfit/pull/505)
• tests/test_trainer.py::TrainerDifferentiableHeadTest::test_trainer_max_length_exceeds_max_acceptable_length => warning is not trigger and don't know why. It also fails on https://github.com/huggingface/setfit/pull/505 which makes me think it's not related to this PR.*

cc @tomaarsen I'm setting this PR as "ready for review". Please let me know if you have any comments.

[tomaarsen]

Hello!

Apologies for the delay! I've merged these changes into main and resolved the remaining outstanding issues as well. I expect this'll all be included in a release quite soon (this week?). Thanks a bunch for making this PR!

• Tom Aarsen