Drop ubutnu 20.04 #17

Job	Run time
multi-arch-test (armv6, bookworm)	4m 17s
multi-arch-test (armv7, bookworm)	4m 18s
multi-arch-test (aarch64, bookworm)	4m 18s
multi-arch-test (s390x, bookworm)	1s
multi-arch-test (ppc64le, bookworm)	1m 24s
multi-arch-test (armv7, ubuntu_latest)	1m 59s
multi-arch-test (aarch64, ubuntu_latest)	4m 19s
multi-arch-test (s390x, ubuntu_latest)	1s
multi-arch-test (ppc64le, ubuntu_latest)	13s
multi-arch-test (armv7, ubuntu22.04)	1m 54s
multi-arch-test (aarch64, ubuntu22.04)	4m 19s
multi-arch-test (s390x, ubuntu22.04)	1s
multi-arch-test (ppc64le, ubuntu22.04)	6s
multi-arch-test (armv6, alpine_latest)	4m 19s
multi-arch-test (armv7, alpine_latest)	4m 18s
multi-arch-test (aarch64, alpine_latest)	4m 20s
multi-arch-test (riscv64, alpine_latest)	1s
multi-arch-test (s390x, alpine_latest)	1s
multi-arch-test (ppc64le, alpine_latest)	1m 29s
	41m 38s

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