Add support for the free-threaded build #398

Job	Run time
make_linux_matrix	3s
python_sdist	13s
make_windows_matrix	4s
make_run_parallel_matrix	3s
clang_TSAN	4m 32s
make_macos_matrix	4s
pytest-run-parallel (macos-latest, 3.14t-dev)	4m 19s
pytest-run-parallel (ubuntu-latest, 3.14t-dev)	4m 31s
pytest-run-parallel (windows-latest, 3.14t-dev)	1m 38s
macos (cp314-macosx_x86_64, macos-13)	7m 33s
macos (cp314t-macosx_x86_64, macos-13)	9m 8s
macos (cp314-macosx_arm64, 11.0, arch -arm64 bash --noprofile --norc -eo pipefail {0})	4m 19s
macos (cp314t-macosx_arm64, 11.0, arch -arm64 bash --noprofile --norc -eo pipefail {0})	4m 47s
windows (cp314-win_amd64)	1m 31s
windows (cp314-win_arm64, windows-11-arm)	2m 52s
windows (cp314-win32)	1m 32s
windows (cp314t-win_amd64)	1m 41s
windows (cp314t-win32)	1m 33s
linux (cp314-manylinux_x86_64, x86_64)	5m 10s
linux (cp314t-musllinux_x86_64, x86_64)	5m 55s
linux (cp314-musllinux_x86_64, x86_64)	6m 0s
linux (cp314t-manylinux_x86_64, x86_64)	5m 7s
linux (cp311-musllinux_i686, i686)	5m 8s
linux (cp313-manylinux_i686, i686)	5m 13s
linux (cp39-manylinux_aarch64, aarch64)	4m 21s
linux (cp314-musllinux_aarch64, aarch64)	4m 36s
linux (cp314t-musllinux_aarch64, aarch64)	4m 59s
linux (cp314-manylinux_aarch64, aarch64)	4m 27s
linux (cp314t-manylinux_aarch64, aarch64)	4m 53s
windows (cp314t-win_arm64, windows-11-arm)	2m 29s
merge_artifacts	2s
check	2s
	1h 48m 45s

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