Fixup perl-version to use singular #1436

Job	Run time
List perl versions [buster]	2s
List perl versions [bookworm]	4s
List perl versions [bookworm defaults]	5s
Build latest (bookworm)	2m 31s
Build latest	2m 34s
Build latest (buster)	19s
Build versions for buster (5.10)	18s
Build versions for buster (5.18)	21s
Build versions for buster (5.8)	19s
Build versions for buster (5.12)	20s
Build versions for buster (5.16)	19s
Build versions for buster (5.26)	20s
Build versions for buster (5.14)	20s
Build versions for buster (5.24)	18s
Build versions for buster (5.20)	21s
Build versions for buster (5.22)	22s
Build versions for buster (5.30)	16s
Build versions for buster (5.34)	17s
Build versions for buster (5.36)	17s
Build versions for buster (5.28)	18s
Build versions for buster (5.32)	16s
Build versions for buster (5.40)	20s
Build versions for buster (5.38)	20s
Build versions for bookworm (5.42, true)	7s
Build versions for bookworm (5.36, 5.38, 5.40, false)	6s
	11m 10s

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