ci: cashing transformers

[Borda]

What does this PR do?

The original data folder was set as useless after periodic cleaning after the script finish, but even docstest takes long because of permanent downloading models...

Before submitting

• [x] Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• [x] Did you read the contributor guideline, Pull Request section?
• [x] Did you make sure your PR does only one thing, instead of bundling different changes together?
• [ ] Did you make sure to update the documentation with your changes?
• [ ] Did you write any new necessary tests? [not needed for typos/docs]
• [ ] Did you verify new and existing tests pass locally with your changes?
• [ ] If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

• [x] Is this pull request ready for review? (if not, please submit in draft mode)

Anyone in the community is free to review the PR once the tests have passed. If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov[bot]]

Codecov Report

Merging #1600 (42cbeab) into master (76d14dc) will decrease coverage by 14%. The diff coverage is 100%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1600 +/- ## ======================================== - Coverage 86% 71% -14% ======================================== Files 291 291 Lines 12874 12874 ======================================== - Hits 11017 9154 -1863 - Misses 1857 3720 +1863 ```