Add support for python 3.12 #2608

Job	Run time
jsonschema	0s
asdf-schemas / Load tox environments	5s
core / Load tox environments	10s
asdf-schemas / asdf-standard (ubuntu-latest)	1m 14s
asdf-schemas / asdf-transform-schemas (ubuntu-latest)	1m 21s
asdf-schemas / asdf-unit-schemas (ubuntu-latest)	48s
core / Python 3.11 coverage	12m 16s
core / Python 3.10 coverage	9m 33s
core / Python 3.9 coverage	11m 2s
compatibility / Load tox environments	5s
dev / Load tox environments	5s
package / Build source and wheel distribution	6m 18s
test / Load tox environments	11s
oldest / Load tox environments	5s
compatibility / compatibility (ubuntu-latest)	3m 1s
oldest / py39-oldestdeps-parallel (ubuntu-latest)	1m 53s
dev / py39-devdeps-parallel (ubuntu-latest)	4m 0s
dev / py310-devdeps-parallel (ubuntu-latest)	3m 41s
dev / py311-devdeps-parallel (ubuntu-latest)	4m 3s
test / py39-parallel (macos-latest)	2m 45s
test / py39-parallel (windows-latest)	2m 53s
	1h 5m 29s

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