local install fails with Python 3.14 because docs dependency `watchfiles` cannot build

[kittauri]

Local make install fails when uv selects CPython 3.14. CI appears to pass, likely because it uses a different Python version.

The failure comes from the docs dependency chain:

voltolighttheme-docs
└── sphinx-autobuild
    └── watchfiles==1.0.4

watchfiles==1.0.4 builds with PyO3 0.23.3, which supports Python up to 3.13.

Steps to reproduce

1. Use Python 3.14
2. Use a fresh repository of Volto-Light-Theme (git clone ...)
3. run make install

Relevant log

Using CPython 3.14.0

× Failed to build `watchfiles==1.0.4`
╰─▶ Call to `maturin.build_wheel` failed

error: the configured Python interpreter version (3.14) is newer than PyO3's maximum supported version (3.13)

hint: `watchfiles` (v1.0.4) was included because `voltolighttheme-docs` depends on `sphinx-autobuild`
make: *** [Makefile:106: install] Fehler 2

Actual behavior

On a machine where uv selects Python 3.14, installation fails while building watchfiles.

Expected behavior

Local install should use a supported Python version and complete successfully.

Note

There is also a Makefile warning:
Makefile:37: Warnung: undefinierte Variable „PYTHON_VERSION“
coming from

volto-light-theme/backend/Makefile

Line 37 in b514906

UV_VENV_ARGS := --python=$(PYTHON_VERSION)