Bump actions/checkout from 3 to 4 (#1015) #590

Job	Run time
coverage	4m 40s
docs	3m 12s
lint	3m 4s
Rust unit tests (ubuntu-latest)	3m 43s
Rustfmt	9s
typecheck	1m 51s
Rust unit tests (macos-latest)	2m 38s
test (macos-latest, 3.8)	9m 41s
Rust unit tests (windows-latest)	5m 28s
test (macos-latest, 3.9)	7m 38s
test (macos-latest, 3.10)	7m 54s
test (macos-latest, 3.11)	9m 1s
test (macos-latest, 3.12-dev)	10m 34s
test (ubuntu-latest, 3.8)	7m 9s
test (ubuntu-latest, 3.9)	6m 49s
test (ubuntu-latest, 3.10)	5m 49s
test (ubuntu-latest, 3.11)	6m 4s
test (ubuntu-latest, 3.12-dev)	8m 37s
test (windows-latest, 3.8)	7m 50s
test (windows-latest, 3.9)	7m 47s
test (windows-latest, 3.10)	7m 52s
test (windows-latest, 3.11)	10m 1s
test (windows-latest, 3.12-dev)	10m 38s
	2h 28m 9s

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