Update Ubuntu and actions/checkout #3

Job	Run time
Build (qemu_x86_defconfig, glibc)	54m 30s
Build (qemu_x86_defconfig, uclibc)	48m 22s
Build (qemu_x86_defconfig, musl)	47m 50s
Build (qemu_x86_64_defconfig, glibc)	55m 4s
Build (qemu_x86_64_defconfig, uclibc)	49m 51s
Build (qemu_x86_64_defconfig, musl)	49m 25s
Build (raspberrypi4_defconfig, glibc)	1h 7m 9s
Build (raspberrypi4_defconfig, uclibc)	1h 5m 57s
Build (raspberrypi4_defconfig, musl)	1h 3m 12s
Build (raspberrypi4_64_defconfig, glibc)	1h 12m 54s
Build (raspberrypi4_64_defconfig, uclibc)	1h 8m 48s
Build (raspberrypi4_64_defconfig, musl)	1h 12m 7s
Build (qemu_ppc64le_pseries_defconfig, glibc)	1h 1m 8s
Build (qemu_ppc64le_pseries_defconfig, uclibc)	1h 4m 9s
Build (qemu_ppc64le_pseries_defconfig, musl)	57m 47s
Build (qemu_mips32r2_malta_defconfig, glibc)	51m 39s
Build (qemu_mips32r2_malta_defconfig, uclibc)	50m 27s
Build (qemu_mips32r2_malta_defconfig, musl)	46m 57s
Build (qemu_mips64_malta_defconfig, glibc)	51m 55s
Build (qemu_mips64_malta_defconfig, uclibc)	48m 18s
Build (qemu_mips64_malta_defconfig, musl)	49m 25s
	19h 56m 54s

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