remove six #6

Job	Run time
build (3.8, ubuntu-latest, base)	14s
build (3.8, ubuntu-latest, optional)	1m 37s
build (3.8, windows-latest, base)	40s
build (3.8, windows-latest, optional)	2m 6s
build (3.9, ubuntu-latest, base)	16s
build (3.9, ubuntu-latest, optional)	1m 40s
build (3.9, windows-latest, base)	56s
build (3.9, windows-latest, optional)	1m 57s
build (3.10, ubuntu-latest, base)	18s
build (3.10, ubuntu-latest, optional)	1m 36s
build (3.10, windows-latest, base)	49s
build (3.10, windows-latest, optional)	2m 8s
build (3.11, ubuntu-latest, base)	20s
build (3.11, ubuntu-latest, optional)	1m 39s
build (3.11, windows-latest, base)	55s
build (3.11, windows-latest, optional)	2m 1s
build (3.12, ubuntu-latest, base)	26s
build (3.12, ubuntu-latest, optional)	1m 33s
build (3.12, windows-latest, base)	58s
build (3.12, windows-latest, optional)	2m 4s
build (pypy-3.10, ubuntu-latest, base)	30s
build (3.8, ubuntu-latest, oldest)	1h 7m 30s
	1h 32m 13s

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