Fix CF tests due to new xarray release

[mraspaud]

This is due to pydata/xarray#7388 not being solved yet.

[codecov]

Codecov Report

Merging #2522 (51c9c1c) into main (fcea851) will decrease coverage by 0.01%.
The diff coverage is 97.72%.

@@            Coverage Diff             @@
##             main    #2522      +/-   ##
==========================================
- Coverage   94.96%   94.96%   -0.01%     
==========================================
  Files         343      347       +4     
  Lines       50771    50921     +150     
==========================================
+ Hits        48216    48358     +142     
- Misses       2555     2563       +8     

Flag	Coverage Δ
behaviourtests	4.32% <2.69%> (+<0.01%)	⬆️
unittests	95.57% <97.72%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
satpy/writers/cf/crs.py	86.66% <86.66%> (ø)
satpy/_scene_converters.py	92.30% <92.30%> (ø)
satpy/writers/cf_writer.py	95.12% <97.86%> (-0.54%)	⬇️
satpy/scene.py	93.59% <100.00%> (-0.01%)	⬇️
satpy/tests/scene_tests/test_conversions.py	100.00% <100.00%> (ø)
satpy/tests/writer_tests/test_cf.py	99.58% <100.00%> (+0.01%)	⬆️
satpy/writers/cf/__init__.py	100.00% <100.00%> (ø)
satpy/writers/cf/coords_attrs.py	100.00% <100.00%> (ø)