Bump actions/checkout from 2 to 4 (#278) #172

Job	Run time
sdist	2m 3s
cibuildwheel ubuntu-22.04/x86_64/cpython/many	7m 8s
cibuildwheel ubuntu-22.04/x86_64/cpython/musl	5m 57s
cibuildwheel ubuntu-22.04/x86_64/pypy/many	3m 17s
cibuildwheel ubuntu-22.04/arm64/cpython/many	1h 13m 45s
cibuildwheel ubuntu-22.04/arm64/cpython/musl	13m 16s
cibuildwheel ubuntu-22.04/arm64/pypy/many	48m 15s
cibuildwheel macos-12/x86_64/cpython/many	19m 25s
cibuildwheel macos-12/x86_64/pypy/many	12m 2s
cibuildwheel macos-12/arm64/cpython/many	6m 48s
upload_all	0s
	3h 11m 56s

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