Continuous Integration

Update release and ci workflows to use `GITHUB_OUTPUT` and bump `actions/checkout` to v4. #739

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Run time

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Job	Run time
lint	51s
build (3.7)	55s
build (3.8)	53s
build (3.9)	56s
build (3.10)	1m 5s
build (pypy3.8)	1m 17s
	5m 57s