Appease mypy #122

Job	Run time
workflow-keepalive	0s
check (3.7)	42s
check (3.8)	1m 19s
check (3.9)	1m 4s
check (3.10)	1m 1s
check (3.11)	1m 4s
check-distro (debian:unstable)	2m 10s
check-distro (debian:testing)	1m 36s
check-distro (debian:stable)	2m 14s
check-distro (debian:oldstable)	1m 24s
check-distro (ubuntu:devel)	1m 21s
check-distro (ubuntu:rolling)	1m 44s
check-distro (ubuntu:latest)	1m 49s
	17m 28s

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