Fix setup.sh for unix compatibility #2044

Job	Run time
build-spidermonkey-unix (macos-14, 3.10)	13m 35s
build-spidermonkey-unix (ubuntu-22.04, 3.10)	14m 33s
build-spidermonkey-win	1m 27s
build-spidermonkey-unix (macos-15-intel, 3.10)	14m 45s
sdist	47s
build-spidermonkey-unix (ubuntu-22.04-arm, 3.10)	12m 12s
publish	1s
publish-nightly	1s
build-and-test	1s
publish-archive	1s
	57m 23s

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