Fix docs-build step

[Miauwkeru]

• move tests/data to tests/_data
• Fix docs-build step

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.17%. Comparing base (1f947c2) to head (9384d00).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #19   +/-   ##
=======================================
  Coverage   89.17%   89.17%           
=======================================
  Files           4        4           
  Lines         268      268           
=======================================
  Hits          239      239           
  Misses         29       29           

Flag	Coverage Δ
unittests	89.17% <ø> (ø)

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