PYTHON-5047 Do not run nightly release check on forks #1603

Job	Run time
Make SDist	34s
Build wheels for manylinux_x86_64	2m 23s
Build wheels for manylinux_aarch64	11m 23s
Build wheels for manylinux_ppc64le	10m 49s
Build wheels for manylinux_s390x	11m 42s
Build wheels for manylinux_i686	2m 25s
Build wheels for win_amd6	4m 2s
Build wheels for win32	6m 20s
Build wheels for macos	5m 1s
Download Wheels	7s
	54m 46s

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