Support Py_GIL_DISABLED (#206)

* Add free-threaded Python 3.14t to the testing

* Support Py_GIL_DISABLED

Do not set py_limited_api when Py_GIL_DISABLED == 1, since it
will be rejected as shown:

  File "/usr/lib/python3.14t/site-packages/setuptools/_distutils/cmd.py", line 135, in ensure_finalized
    self.finalize_options()
    ~~~~~~~~~~~~~~~~~~~~~^^
  File "<string>", line 82, in finalize_options
  File "/usr/lib/python3.14t/site-packages/setuptools/command/bdist_wheel.py", line 250, in finalize_options
    self._validate_py_limited_api()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/lib/python3.14t/site-packages/setuptools/command/bdist_wheel.py", line 285, in _validate_py_limited_api
    raise ValueError(
    ...<4 lines>...
    )
ValueError: `py_limited_api='cp314'` not supported. `Py_LIMITED_API` is currently incompatible with `Py_GIL_DISABLED`.See python/cpython#111506.

---------

Co-authored-by: Christian Clauss <cclauss@me.com>

Author: zmedico

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"]
     steps:
       - name: Set git to use LF on Windows
         if: runner.os == 'Windows'

setup.py

@@ -3,6 +3,7 @@
 import re
 import platform
 import sys
+import sysconfig
 from setuptools import find_packages, setup
 from setuptools.command.build_ext import build_ext
 
@@ -76,7 +77,8 @@ def run(self):
     else:
         class BDistWheel(wheel.bdist_wheel.bdist_wheel):
             def finalize_options(self):
-                self.py_limited_api = "cp3{}".format(sys.version_info[1])
+                if sysconfig.get_config_var("Py_GIL_DISABLED") != 1:
+                    self.py_limited_api = "cp{}{}".format(*sys.version_info)
                 wheel.bdist_wheel.bdist_wheel.finalize_options(self)
         cmdclass['bdist_wheel'] = BDistWheel