Clean up unit tests and photutils dependency

[geordie666]

The desitarget unit tests are currently flagging some deprecated modules and functions. Clean those up.

[geordie666]

In particular, the photutils dependency is now pinned to version 1.6.0. We should revisit the best way to maintain this dependency.

[moustakas]

I think #829 addresses at least some of this ticket. Note that I didn't see any issues with photutils there.

[weaverba137]

@geordie666, this ticket is fairly old now, but the pinned photutils dependency is retained even after #838. Do you recall what would be required to unpin this dependency?

[geordie666]

I think we just need to retain a copy of photutils for some of the core code that produces sky-location targets. But, the DESI stack doesn't actually ostensibly support photutils.

But, if the photutils dependency is still working then maybe we don't worry about it until it breaks? It's currently being maintained as an astropy affiliated package, so it likely won't be a problem in the short term.

[weaverba137]

Fortunately, photutils==1.6.0 does not specify a maximum NumPy version, but do we know for sure that the code that depends on photutils will continue to work in Numpy 2, or is it not covered by tests? For reference the current version is photutils==2.2.0.

So basically are you saying that "some version of photutils is required" or that "photutils==1.6.0 is mandatory because later versions will break"?

[geordie666]

Oh, good point. Now that you've updated the other dependencies it may not be necessary to pin photutils to 1.6.0. Certainly the unit tests cover photutils, so this would be worth investigating.

I don't think there's anything special about photutils=1.6.0 other than that it was "the version that worked in our pre-numpy-2 environment."