Add CI checks on free-threaded Python 3.14 #3

Job	Run time
Build ubuntu-22.04 (x86_64) wheels	6m 47s
Build wheels for ARM64 on Windows	16m 59s
Build wheels for AMD64 on windows-latest	11m 56s
Build ubuntu-24.04-arm (aarch64) wheels	9m 10s
Build wheels for arm64 on macos-14	11m 3s
Build source distribution	38s
Build wheels for x86_64 on macos-15-intel	13m 9s
Show artifacts	7s
Publish to PyPI	0s
	1h 9m 49s

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