MNT: numpy 2 and astropy 6.1 compat, bump minversions

[pllim]

Description

This pull request is to address impending numpy 2.0 release.

Fixes #386

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.21%. Comparing base (0edcfb2) to head (570f216).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #387      +/-   ##
==========================================
+ Coverage   96.83%   97.21%   +0.37%     
==========================================
  Files          17       17              
  Lines        2056     2047       -9     
==========================================
- Hits         1991     1990       -1     
+ Misses         65       57       -8     

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[pllim]

@ariedel , does ETC team want to take this for a spin before I merge? This builds synphot C-ext against numpy 2.x ABI but should still be compatible with numpy 1.x to some degree.

[pllim]

Please let me know if you also need an accompanying stsynphot PR though I don't see why because stsynphot does not have C-extension.

[ariedel]

The ETC still uses numpy 1.x, but I've taken this branch for a spin and the ETC functions perfectly well with the changes.