Fix memory leak in cached_property backport

[sfinkens]

Closes #2008 by replacing the existing backport with the cached_property implementation from the Python-3.8 repository.

• Closes abi_l1b reader leaks memory in Python-3.7 #2008
• Tests added

[sfinkens]

Example with one day of ABI data.

Black: Current implementation with Python-3.7
Blue: Fix with Python-3.7

[codecov]

Codecov Report

Merging #2011 (6c9cf22) into main (34bd429) will decrease coverage by 0.01%.
The diff coverage is 83.01%.

@@            Coverage Diff             @@
##             main    #2011      +/-   ##
==========================================
- Coverage   93.56%   93.55%   -0.02%     
==========================================
  Files         281      282       +1     
  Lines       41480    41538      +58     
==========================================
+ Hits        38811    38860      +49     
- Misses       2669     2678       +9     

Flag	Coverage Δ
behaviourtests	4.77% <13.20%> (+<0.01%)	⬆️
unittests	94.08% <83.01%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
satpy/_compat.py	75.00% <75.00%> (-6.82%)	⬇️
satpy/tests/test_compat.py	100.00% <100.00%> (ø)
satpy/tests/reader_tests/test_abi_l2_nc.py	100.00% <0.00%> (ø)
satpy/readers/abi_l2_nc.py	96.00% <0.00%> (+0.76%)	⬆️

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[djhoese]

Where does this solution come from? Stackoverflow? Official CPython docs somewhere?

[djhoese]

If you update line 267 in doc/source/conf.py to say:

    'numpy': ('https://numpy.org/doc/stable', None),

it should fix the build_website failure. Numpy updated their documentation structure.

[sfinkens]

Where does this solution come from? Stackoverflow? Official CPython docs somewhere?

It was an stackoverflow answer that pointed me to the CPython repository: https://stackoverflow.com/a/58592597/5703449

[sfinkens]

'numpy': ('https://numpy.org/doc/stable', None),

Done, thanks!

[coveralls]

Coverage decreased (-0.01%) to 94.012% when pulling 6c9cf22 on sfinkens:fix-cached-property-backport into e27414f on pytroll:main.

[djhoese]

This looks good to me. It is a much more involved solution than I thought it was going to be. I think given that we are removing Python 3.7 support I think we should merge this, make a release, then immediately remove this as part of a PR to drop Python 3.7 support. Thoughts @sfinkens @mraspaud @pnuu ?

Oops @gerritholl you too, thoughts?

[mraspaud]

LGTM as a patch for the last release supporting python 3.7 :)