CI: Use a Ubuntu 20.04 container to keep Ubuntu 20.04 support #1969

Job	Run time
build-spidermonkey-win	11s
build-spidermonkey-unix (macos-14, 3.10)	7s
sdist	31s
build-spidermonkey-unix (macos-13, 3.10)	8s
build-spidermonkey-unix (ubuntu-22.04-arm, 3.10)	15s
build-spidermonkey-unix (ubuntu-22.04, 3.10)	8s
build-and-test (ubuntu-22.04, 3.9)	1m 14s
build-and-test (ubuntu-22.04, 3.12)	1m 31s
build-and-test (ubuntu-22.04, 3.8)	1m 29s
build-and-test (ubuntu-22.04, 3.10)	1m 28s
build-and-test (ubuntu-22.04, 3.11)	1m 34s
build-and-test (ubuntu-22.04, 3.13)	1m 27s
build-and-test (macos-13, 3.10)	1m 57s
build-and-test (macos-13, 3.11)	1m 57s
build-and-test (macos-13, 3.9)	2m 2s
build-and-test (macos-14, 3.8)	1s
build-and-test (macos-13, 3.12)	2m 7s
build-and-test (macos-13, 3.8)	2m 11s
build-and-test (macos-14, 3.10)	1s
build-and-test (windows-2022, 3.11)	1m 54s
build-and-test (macos-14, 3.9)	1s
build-and-test (windows-2022, 3.9)	1m 48s
build-and-test (macos-14, 3.11)	1s
build-and-test (windows-2022, 3.10)	1m 50s
build-and-test (macos-13, 3.13)	1m 55s
build-and-test (macos-14, 3.13)	1s
build-and-test (ubuntu-22.04-arm, 3.13)	1s
build-and-test (ubuntu-22.04-arm, 3.8)	1s
build-and-test (macos-14, 3.12)	1s
build-and-test (ubuntu-22.04-arm, 3.11)	20s
build-and-test (windows-2022, 3.12)	1m 48s
build-and-test (ubuntu-22.04-arm, 3.10)	1s
build-and-test (windows-2022, 3.8)	1m 50s
build-and-test (windows-2022, 3.13)	1m 41s
build-and-test (ubuntu-22.04-arm, 3.9)	19s
build-and-test (ubuntu-22.04-arm, 3.12)	40s
publish-archive	1s
publish	1s
publish-nightly	1s
	34m 34s

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