Use multi-phase init #365

Job	Run time
python_sdist	11s
make_linux_matrix	7s
make_macos_matrix	4s
make_windows_matrix	3s
macos (cp313-macosx_x86_64, macos-13)	25s
macos (cp313-macosx_arm64, 11.0, arch -arm64 bash --noprofile --norc -eo pipefail {0})	19s
linux (cp313t-manylinux_x86_64, true)	50s
linux (cp313-manylinux_x86_64)	50s
linux (cp313-musllinux_x86_64)	44s
windows (cp313-win_amd64)	59s
check	5s
merge_artifacts	0s
	4m 37s

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