Fix build

Author: mitchsayre

CONTRIBUTING.md

@@ -139,6 +139,7 @@ python -m twine upload --repository testpypi dist/*
   they are not already available locally.
 - `python -m build` without `WFLOAT_SHERPA_ONNX_SOURCE_DIR` may fail because
   the wheel build can run from a temporary unpacked source tree.
+- CI wheel builds use normal PEP 517 build isolation through `cibuildwheel`.
 - We currently publish wheels, not a self-contained source distribution. The
   source distribution path should only be documented after it no longer depends
   on an external sibling `sherpa-onnx` checkout.

pyproject.toml

@@ -5,5 +5,4 @@ build-backend = "setuptools.build_meta"
 [tool.cibuildwheel]
 build = "cp38-* cp39-* cp310-* cp311-* cp312-* cp313-*"
 skip = "pp* *-win32 *-manylinux_i686 *-musllinux_*"
-build-frontend = { name = "pip", args = ["--no-build-isolation"] }
 test-command = 'python -c "from wfloat import version, write_wave; print(version)"'