Update outdated CI actions

[AdrianoKF]

The upload_artifact/download_artifact actions were using the outdated NodeJS v16 runtime in version v3, which we depended on.

This commit bumps them to the latest version, addressing the deprecation warnings raised by the release workflow.

Also, the lakeFS sidecar container version needed for the docs builds has been made consistent with the PR workflow (which was using the latest Docker image by default).

See: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to- node-20/

Note to reviewer: Sorry for the whitespace re-formatting - we should probably adopt common YAML formatting settings going forward ;)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.32%. Comparing base (6973b99) to head (173c38e).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #269 +/- ## ======================================= Coverage 94.32% 94.32% ======================================= Files 5 5 Lines 388 388 Branches 72 72 ======================================= Hits 366 366 Misses 13 13 Partials 9 9 ```

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