drop support for Python 3.8

[zacharyburnett]

Numpy is imminently dropping support for Python 3.8

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (ab475dc) 98.01% compared to head (0abbfd7) 98.01%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #155   +/-   ##
=======================================
  Coverage   98.01%   98.01%           
=======================================
  Files           8        8           
  Lines        1209     1209           
=======================================
  Hits         1185     1185           
  Misses         24       24           

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[WilliamJamieson]

The RTD configuration should be redone to use mamba, see https://github.com/astropy/astropy/blob/main/.readthedocs.yaml for an example

[zacharyburnett]

It looks like the docs build is failing with the following:
https://readthedocs.org/projects/roman-datamodels/builds/20119428/

/home/docs/checkouts/readthedocs.org/user_builds/roman-datamodels/checkouts/155/docs/roman_datamodels/datamodels/developer_api.rst:113: WARNING: autosummary: stub file not found 'roman_datamodels.stuserdict.Any'. Check your autosummary_generate setting.

[nden]

@zacharyburnett I wonder if this helps
https://stackoverflow.com/questions/47344477/how-to-exclude-imports-from-automodapi-output/68984608#68984608

[nden]

@zacharyburnett This needs a change log entry

[WilliamJamieson]

• roman_datamodels/src/roman_datamodels/stnode.py

  Lines 27 to 30 in ae1caff

  	if sys.version_info < (3, 9):
  	import importlib_resources
  	else:
  	import importlib.resources as importlib_resources

  should be fixed as this is for python 3.8 support
• Fix merge conflicts.

[PaulHuwe]

LGTM

[nden]

@zacharyburnett There's now an ImportError. Once this is fixed we can merge.

"datamodels-1.0.yaml"
E NameError: name 'importlib_resources' is not defined

[nden]

The change request was addressed, merging.