CI: Use a Ubuntu 20.04 container to keep Ubuntu 20.04 support #1971

Job	Run time
build-spidermonkey-win	12s
build-spidermonkey-unix (macos-13, 3.10)	9s
sdist	31s
build-spidermonkey-unix (ubuntu-22.04, 3.10)	6s
build-spidermonkey-unix (ubuntu-22.04-arm, 3.10)	10s
build-spidermonkey-unix (macos-14, 3.10)	8s
build-and-test (ubuntu-22.04, 3.8)	2m 16s
build-and-test (ubuntu-22.04, 3.9)	2m 33s
build-and-test (ubuntu-22.04, 3.12)	2m 47s
build-and-test (ubuntu-22.04, 3.13)	2m 34s
build-and-test (ubuntu-22.04, 3.10)	1m 58s
build-and-test (macos-13, 3.8)	5m 5s
build-and-test (ubuntu-22.04, 3.11)	2m 16s
build-and-test (macos-13, 3.9)	4m 39s
build-and-test (macos-13, 3.12)	4m 57s
build-and-test (macos-13, 3.11)	5m 4s
build-and-test (macos-13, 3.13)	1s
build-and-test (macos-14, 3.10)	1s
build-and-test (macos-14, 3.9)	8s
build-and-test (macos-14, 3.8)	1s
build-and-test (macos-14, 3.12)	2m 48s
build-and-test (windows-2022, 3.10)	4m 50s
build-and-test (windows-2022, 3.9)	4m 57s
build-and-test (macos-13, 3.10)	4m 54s
build-and-test (macos-14, 3.11)	2m 12s
build-and-test (macos-14, 3.13)	4m 54s
build-and-test (windows-2022, 3.8)	4m 56s
build-and-test (windows-2022, 3.12)	4m 58s
build-and-test (ubuntu-22.04-arm, 3.11)	3m 47s
build-and-test (windows-2022, 3.11)	4m 58s
build-and-test (ubuntu-22.04-arm, 3.10)	4m 42s
build-and-test (ubuntu-22.04-arm, 3.9)	3m 1s
build-and-test (ubuntu-22.04-arm, 3.8)	3m 52s
build-and-test (windows-2022, 3.13)	4m 57s
build-and-test (ubuntu-22.04-arm, 3.13)	2m 42s
build-and-test (ubuntu-22.04-arm, 3.12)	2m 42s
publish	1s
publish-archive	1s
publish-nightly	1s
	1h 40m 49s

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