chore!: Update arviz_example_data artifact to v0.4.3

[github-actions]

This PR updates the Artifacts.toml entry for arviz_example_data to the release v0.4.3.

Before merging, you should check that the selected release is correct and that the tests pass.

[sethaxen]

arviz_example_data v0.4.0 removed the classification and regression datasets, so this is a breaking change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.31%. Comparing base (cd915a0) to head (860a258).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
- Coverage   84.61%   84.31%   -0.31%     
==========================================
  Files           5        5              
  Lines          52       51       -1     
==========================================
- Hits           44       43       -1     
  Misses          8        8              

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[sethaxen]

Failures on macos look like the sporadic ones we've been seeing on ArviZExampleData and are probably not important.