PYTHON-5357 Update changelog for 4.12.1 release #2253

Job	Run time
Make SDist	31s
Build wheels for manylinux_x86_64	2m 40s
Build wheels for manylinux_aarch64	11m 45s
Build wheels for manylinux_ppc64le	11m 17s
Build wheels for manylinux_s390x	11m 49s
Build wheels for manylinux_i686	2m 38s
Build wheels for win_amd6	5m 12s
Build wheels for win32	6m 13s
Build wheels for macos	3m 28s
Download Wheels	9s
	55m 42s

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