fix(setup): don't force abi3 wheel tag on free-threaded builds

[JSap0914]

Problem

On free-threaded CPython (Py_GIL_DISABLED), tree-sitter-python builds an extension without the limited API — this is already correct, because the Extension sets:

py_limited_api=not get_config_var("Py_GIL_DISABLED")

So on a free-threaded interpreter the produced .so uses the full, version-specific ABI (e.g. _binding.cpython-314t-darwin.so).

However, BdistWheel.get_tag unconditionally rewrote any cp* wheel tag to cp310/abi3:

if python.startswith("cp"):
    python, abi = "cp310", "abi3"

The result is a wheel tagged as stable-ABI (cp310-abi3) whose contents are a non-abi3, free-threaded extension. The wheel tag lies about the ABI, which breaks installation/import on free-threaded interpreters (reported in #337 as ImportError: symbol not found in flat namespace '_tree_sitter_python_external_scanner_create' / an abi3 wheel that is unusable on 3.14t).

Fix

Gate the abi3 rewrite on the same Py_GIL_DISABLED condition already used for py_limited_api, so the wheel tag matches the ABI the extension was actually built against. This mirrors the fix suggested by the reporter (@ngoldbaum) in #337, expressed against the existing get_config_var import so the two ABI decisions stay in sync.

-        if python.startswith("cp"):
+        if python.startswith("cp") and not get_config_var("Py_GIL_DISABLED"):
             python, abi = "cp310", "abi3"

• GIL builds are unaffected: still tagged cp310-abi3.
• Free-threaded builds are now tagged to match their real ABI (e.g. cp314-cp314t).

Verification

Built and installed the wheel with cpython-3.14.6+freethreaded and a regular GIL 3.13:

Interpreter	Wheel tag before	Wheel tag after	import tree_sitter_python
3.14t (free-threaded)	cp310-abi3 (wrong)	cp314-cp314t (correct)	OK
3.13 (GIL)	cp310-abi3	cp310-abi3 (unchanged)	OK

After the fix, on free-threaded 3.14t the wheel WHEEL metadata reports Tag: cp314-cp314t-..., matching the bundled _binding.cpython-314t-darwin.so, and the existing binding test (bindings/python/tests/test_binding.py) passes on both interpreters.

Closes #337

[ngoldbaum]

Thanks!

Free-threaded 3.15 and newer does support limited API builds, so you might as well account for that right now and make the build skip it only on 3.14 and older.

[ngoldbaum]

Although I don't know offhand if tree-sitter's C extensions actually do build on abi3t, see https://docs.python.org/3.15/howto/abi3t-migration.html#abi3t-migration-howto