MNT correct publish_dir for html files of asv benchmarks

[MatthewSZhang]

Checklist

• Used a personal fork to propose changes
• A reference to a related issue: MNT index html is missing in asv benchmarks #142
• A description of the changes: fix the publish dir for html files

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (b17409b) to head (f7095fe).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #143   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            9         9           
  Lines          647       647           
=========================================
  Hits           647       647           

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