Drop jsonschema #2218

Job	Run time
asdf / Load tox environments	8s
astropy / Load tox environments	8s
third-party / Load tox environments	9s
stsci / Load tox environments	8s
astropy / asdf-astropy (ubuntu-latest)	4m 33s
third-party / weldx (ubuntu-latest)	3m 56s
third-party / sunpy (ubuntu-latest)	3m 14s
third-party / dkist (ubuntu-latest)	11m 56s
stsci / gwcs (ubuntu-latest)	1m 34s
stsci / jwst (ubuntu-latest)	17m 16s
stsci / stdatamodels (ubuntu-latest)	2m 44s
stsci / stpipe (ubuntu-latest)	49s
stsci / roman_datamodels (ubuntu-latest)	1m 36s
asdf / asdf-wcs-schemas (ubuntu-latest)	1m 25s
asdf / asdf-coordinates-schemas (ubuntu-latest)	2m 43s
	52m 19s

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