CI: Use a Ubuntu 20.04 container to keep Ubuntu 20.04 support #1972

Job	Run time
sdist	34s
build-spidermonkey-win	11s
build-spidermonkey-unix (ubuntu-22.04, 3.10)	7s
build-spidermonkey-unix (ubuntu-22.04-arm, 3.10)	9s
build-spidermonkey-unix (macos-13, 3.10)	9s
build-spidermonkey-unix (macos-14, 3.10)	9s
build-and-test (ubuntu-22.04, 3.8)	2m 45s
build-and-test (ubuntu-22.04, 3.9)	3m 0s
build-and-test (ubuntu-22.04, 3.10)	3m 2s
build-and-test (macos-13, 3.8)	4m 53s
build-and-test (ubuntu-22.04, 3.13)	3m 2s
build-and-test (ubuntu-22.04, 3.12)	3m 3s
build-and-test (macos-13, 3.9)	2m 15s
build-and-test (macos-13, 3.13)	2m 58s
build-and-test (macos-13, 3.10)	1s
build-and-test (ubuntu-22.04, 3.11)	2m 35s
build-and-test (macos-13, 3.12)	5m 42s
build-and-test (macos-13, 3.11)	1s
build-and-test (macos-14, 3.11)	2m 46s
build-and-test (macos-14, 3.12)	1s
build-and-test (macos-14, 3.10)	3m 15s
build-and-test (macos-14, 3.8)	3m 35s
build-and-test (windows-2022, 3.8)	5m 45s
build-and-test (macos-14, 3.9)	2m 34s
build-and-test (macos-14, 3.13)	54s
build-and-test (windows-2022, 3.12)	5m 48s
build-and-test (windows-2022, 3.13)	5m 42s
build-and-test (windows-2022, 3.10)	5m 39s
build-and-test (windows-2022, 3.9)	5m 41s
build-and-test (ubuntu-22.04-arm, 3.9)	3m 24s
build-and-test (ubuntu-22.04-arm, 3.10)	3m 53s
build-and-test (windows-2022, 3.11)	5m 47s
build-and-test (ubuntu-22.04-arm, 3.13)	2m 47s
build-and-test (ubuntu-22.04-arm, 3.11)	3m 32s
build-and-test (ubuntu-22.04-arm, 3.12)	3m 36s
build-and-test (ubuntu-22.04-arm, 3.8)	2m 47s
publish-nightly	1s
publish	1s
publish-archive	1s
	1h 42m 5s

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