remove xarray as hard dependency

[jGaboardi]

This PR removes xarray as hard dependency, which is causing feedstock failures

• xref – CI against Python 3.12 #585 (comment)
• xref – libpysal v4.9.1 conda-forge/libpysal-feedstock#22 (comment)

[jGaboardi]

So with these two failures in test_contiguity.py and test_raster.py , do we want to skipif?

[codecov]

Codecov Report

Merging #629 (c170807) into main (6072541) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main    #629   +/-   ##
=====================================
  Coverage   84.5%   84.5%           
=====================================
  Files        139     139           
  Lines      14967   14972    +5     
=====================================
+ Hits       12642   12647    +5     
  Misses      2325    2325           

Files	Coverage Δ
libpysal/weights/tests/test_contiguity.py	100.0% <100.0%> (ø)
libpysal/weights/tests/test_raster.py	100.0% <100.0%> (ø)

[jGaboardi]

So unless I am missing something obvious we have 2 choices here:

1. Do some minor(?) refactoring in test_contiguity.ContiguityMixin where the da stuff is mixed in with other stuff; or
2. Add xarray to the "testing" section of ci/312-no-optional.yaml

[jGaboardi]

@knaaptime OK, CI running now. Sorry for the confusion 🤣

[jGaboardi]

So is this PR good to merge? And after merge shall we cut a v4.9.2 release? or v4.9.1post1? Or something else?

[knaaptime]

i think this is a bugfix (and we're changing the dependencies) so id do 492. I think its probably ready to go, but was gonna wait for martin to have a look since you and i both touched the pr

[jGaboardi]

Agreed

[martinfleis]

pending green ci :)