Add py free-threaded support #1715

Job	Run time
Build and test with .NET	19s
Build and test cmake:gcc	1m 4s
Build and test cmake:clang	59s
Build and test cmake:clang-old	43s
Build and test cmake:gcc-old	56s
Build and test cmake:package	1m 6s
Build and test cmake:clang:asan	1m 17s
Build and test cmake:static	44s
Build and test cmake:clang:tsan	1m 5s
Build and test cmake:clang:ubsan	1m 1s
Build and test cmake:qemu-arm-neon-gcc	2m 20s
Build and test cmake-osx:clang	39s
Build and test cmake-osx:gcc	20s
Build and test cmake-win64:msvc-rel	39s
Build and test cmake-ios:clang	25s
Build and test cmake-win64:msvc-dbg	45s
Build and test python3.10:clang	1m 35s
Build and test fuzz:clang	47s
Build and test python3.14:clang	1m 34s
Build and test python3.14-win	1m 56s
Build and test maven	1m 3s
Build and test bazel:go	1m 17s
Build and test bazel-osx:root	46s
Build and test bazel:root	52s
Build and test bazel:java	2m 14s
Build and test bazel-win:root	1m 10s
Build and test bazel-osx:java	3m 45s
Build and test bazel-osx:research	42s
Build and test bazel-win:research	1m 7s
Build and test bazel-osx:go	2m 21s
Build and test bazel:research	1m 38s
Build and test python3.14t:clang	1m 45s
	38m 54s

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