Change setup to setup_method in nucal test

[jsdillon]

EDIT: I've also editing the path handling where .uvh5 was replaced with .interleave_{inum}.uvh5, which affecting some of the path info in github actions. So now only .uvh5 in the basename can be replaced because I'm using code like:
iname = os.path.join(os.path.dirname(output_name), os.path.basename(output_name).replace('.uvh5', f'.interleave_{inum}.uvh5'))

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d45df27) 97.17% compared to head (ff5d892) 97.17%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #930   +/-   ##
=======================================
  Coverage   97.17%   97.17%           
=======================================
  Files          23       23           
  Lines       10507    10507           
=======================================
  Hits        10210    10210           
  Misses        297      297           

Flag	Coverage Δ
unittests	97.17% <100.00%> (ø)

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