Revert to artifact upload/download to v3 for 2.8.0 release

[IAlibay]

Related to #4783

Artifacts are no longer mutable in v4, which means that the workflow will need to changes to allow for multiple artifacts to be uploaded at the same time.

To avoid spending a lot of time fixing multiple things at the same time (and blocking through review), we rever to the v3 version. After the v2.8.0 release of MDAnalysis, work will be done to update the deploy workflow to v4.

Developers certificate of origin

• I certify that this contribution is covered by the LGPLv2.1+ license as defined in our LICENSE and adheres to the Developer Certificate of Origin.

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📚 Documentation preview 📚: https://mdanalysis--4784.org.readthedocs.build/en/4784/

[IAlibay]

This does not trigger any relevant CI workflows, so merging as-is.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.64%. Comparing base (5eeedd6) to head (ba7ba01).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4784      +/-   ##
===========================================
- Coverage    93.66%   93.64%   -0.03%     
===========================================
  Files          177      189      +12     
  Lines        21742    22808    +1066     
  Branches      3055     3055              
===========================================
+ Hits         20365    21358     +993     
- Misses         930     1003      +73     
  Partials       447      447              

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