Bump actions/checkout from 5 to 6 in the github-actions group #1321

Job	Run time
mypy	23s
ruff	9s
sdist	59s
parse_sdl (macos-latest, 3.2.16)	25s
parse_sdl (windows-latest, 3.2.16)	35s
test-docs	1m 58s
linux-wheels (aarch64, cp310-manylinux*)	4m 11s
build (ubuntu-latest, pypy-3.10, x64)	3m 6s
build-macos (pp310-*)	4m 32s
build (windows-latest, 3.10, x64)	2m 56s
tox (ubuntu-latest)	2m 20s
linux-wheels (aarch64, pp310-manylinux*)	3m 35s
build (windows-latest, 3.10, x86)	3m 34s
linux-wheels (x86_64, pp310-manylinux*)	3m 43s
build (ubuntu-latest, 3.10, x64)	3m 54s
build-macos (cp310-*_universal2)	2m 55s
linux-wheels (x86_64, cp310-manylinux*)	4m 20s
build (windows-latest, pypy-3.10, x64)	5m 21s
pyodide	2m 20s
publish	0s
	51m 16s

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