MNT: Clean up _astropy_init.py

[pllim]

Because config stuff is unnecessary and removed in astropy v6.0, see:

• astropy/astropy#15466

And I don't think you even use it anyway?

This is failing our devdeps job in Jdaviz CI (e.g., https://github.com/spacetelescope/jdaviz/pull/2409) because even though Jdaviz does not use this package, glue-astronomy refuses to make this package optional.

cc @astrofrog @keflavich

[pllim]

Failure is unrelated. Looks like you need to clean up your CI infrastructure, which is out of scope here.

[codecov[bot]]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Files	Coverage Δ
spectral_cube/_astropy_init.py	77.77% <100.00%> (+24.20%)	:arrow_up:

... and 1 file with indirect coverage changes

:loudspeaker: Thoughts on this report? Let us know!.

[keflavich]

@astrofrog @e-koch I'm good to merge this, even with CI red, as long as we're confident we're not using it.

We do need to update CI elsewhere.

[e-koch]

Agreed on merging now and fixing the CI issue elsewhere.

[pllim]

PSA: You might wanna release before astropy v6.0 comes out at the end of the year. See https://github.com/astropy/astropy/wiki/Release-Calendar

[pllim]

Thanks for the merge!