CI: Build on Ubuntu 20.04 for arm64 linux release #1999

Job	Run time
build-spidermonkey-unix (macos-13, 3.10)	26s
build-spidermonkey-unix (macos-14, 3.10)	18s
sdist	31s
build-spidermonkey-win	16s
build-spidermonkey-unix (ubuntu-22.04-arm, 3.10)	1m 34s
build-spidermonkey-unix (ubuntu-22.04, 3.10)	14s
build-and-test	0s
publish	-1s
publish-archive	-1s
publish-nightly	-1s
	3m 16s

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