fix(ci): adjust container name in nightly build

[duposyl]

Addresses nightly build failure, see https://github.com/ansys/pystk/actions/runs/18236847476/job/51932338086#step:6:26

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.65%. Comparing base (a2c719c) to head (bad228f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #851   +/-   ##
=======================================
  Coverage   89.65%   89.65%           
=======================================
  Files          66       66           
  Lines      188712   188712           
  Branches     1360     1360           
=======================================
  Hits       169198   169198           
  Misses      19122    19122           
  Partials      392      392           

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[jorgepiloto]

Thanks for fixing this, @duposyl