CI: add a nightly wheel upload

[ianhi]

Nightly upload the anaconda scipy-nightly-wheels channel to enable easier testing by downstream packages

Attn @jhamman

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.82%. Comparing base (878d2b3) to head (6543fac).
⚠️ Report is 1 commits behind head on main.

❌ Your project status has failed because the head coverage (99.82%) is below the target coverage (100.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #787      +/-   ##
===========================================
- Coverage   100.00%   99.82%   -0.18%     
===========================================
  Files           64       64              
  Lines         2804     2804              
===========================================
- Hits          2804     2799       -5     
- Misses           0        5       +5     

see 1 file with indirect coverage changes

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[ianhi]

@d-v-b I don't think the project was ever fully created. see scientific-python/upload-nightly-action#142 so this may lead to failures