Remove CI on nightly

[gdalle]

Fix #295

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.27%. Comparing base (599ef81) to head (2cc587e).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #374   +/-   ##
=======================================
  Coverage   97.27%   97.27%           
=======================================
  Files         118      118           
  Lines        6874     6874           
=======================================
  Hits         6687     6687           
  Misses        187      187           

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[etiennedeg]

What does the allow failure do if the tests still error when nightly errors?

[gdalle]

I think it does at least allow the CI badge on README to be green, but I'm not sure of the internals. See https://discourse.julialang.org/t/ignoring-nightly-failure-for-ci-badge/98028/5?u=gdalle for a discussion

Beyond the green checks and red crosses, it also comes down to a philosophical issue of whether we should test on nightly or not. I'd be favorable to testing on the next release candidate as soon as it comes out instead, because it's likely to be more polished and e.g. not make JET or Aqua fail