Handle GWCS for specutils 2.0 compatibility #141

Job	Run time
initial_checks / Load tox environments	7s
initial_checks / codestyle (ubuntu-latest)	15s
tests / Load tox environments	5s
tests / py38-test (ubuntu-latest)	36s
tests / py39-test (ubuntu-latest)	1m 20s
tests / py310-test-dev (ubuntu-latest)	2m 48s
tests / py311-test-dev (ubuntu-latest)	2m 57s
tests / py312-test-dev (ubuntu-latest)	4m 6s
tests / py311-test (macos-latest)	47s
tests / py38-test (windows-latest)	1m 12s
tests / py39-test-dev (windows-latest)	2m 8s
tests / py310-test-dev (macos-latest)	2m 57s
publish	0s
	19m 18s

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