Bump actions/checkout from 3 to 4 #1061

Job	Run time
check_links	1m 47s
Build, test and code coverage (ubuntu-latest, 3.8)	2m 7s
Test Docs	4m 8s
Build, test and code coverage (ubuntu-latest, 3.11)	1m 59s
Test Lint	51s
Build, test and code coverage (macos-latest, 3.8)	3m 39s
Make SDist	32s
Test Minimum Versions	2m 42s
Build, test and code coverage (macos-latest, 3.11)	5m 53s
Test Prereleases	43s
Build, test and code coverage (windows-latest, 3.8)	4m 9s
Build, test and code coverage (windows-latest, 3.11)	5m 39s
check_release	2m 25s
Build, test and code coverage (windows-latest, 3.9)	5m 39s
Build, test and code coverage (ubuntu-latest, pypy-3.8)	5m 33s
Build, test and code coverage (ubuntu-latest, 3.12)	2m 45s
Build, test and code coverage (macos-latest, 3.10)	4m 51s
Install from SDist and Test	1m 48s
coverage	0s
tests_check	1s
	57m 11s

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