The test-no-python-version test was failing because hatchling's
dependency on pathspec was incompatible with Python 3.9,
causing a TypeError during the build process.
Fixed by switching from hatchling to uv_build backend
(0.9.22-0.10.0 range) which is fully compatible with
Python 3.9. The uv.lock file is updated to reflect the
new build backend and latest compatible versions of dependencies.