Add py free-threaded support #1695

Job	Run time
Build and test with .NET	23s
Build and test cmake:gcc-old	41s
Build and test cmake:package	1m 8s
Build and test cmake:clang	45s
Build and test cmake:static	44s
Build and test cmake:clang-old	46s
Build and test cmake:clang:tsan	1m 3s
Build and test cmake:gcc	43s
Build and test cmake:clang:asan	1m 2s
Build and test cmake-win64:msvc-dbg	1m 45s
Build and test cmake:qemu-arm-neon-gcc	1m 23s
Build and test cmake-win64:msvc-rel	53s
Build and test python3.14:clang	27s
Build and test cmake:clang:ubsan	1m 10s
Build and test cmake-ios:clang	20s
Build and test python3.14t:clang	35s
Build and test fuzz:clang	55s
Build and test cmake-osx:clang	24s
Build and test bazel:research	45s
Build and test cmake-osx:gcc	26s
Build and test bazel-win:root	1m 44s
Build and test bazel:java	2m 17s
Build and test bazel:root	59s
Build and test maven	1m 2s
Build and test bazel-osx:java	3m 42s
Build and test bazel-osx:root	1m 5s
Build and test bazel-osx:go	2m 17s
Build and test bazel:go	1m 19s
Build and test python3.14-win	37s
Build and test bazel-win:research	1m 1s
Build and test bazel-osx:research	1m 12s
	33m 33s

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