package makedepends on itself, making it difficult to bootstrap for newer Python versions

Description:

The PKGBUILD makedepends on itself, other than python-installer, which uses PYTHONPATH=src to use the new version of python-installer to install itself.

This makes it so that in bootstrap situations it's more complicated than necessary to install new versions of build and installer.

python-build could do the same as python-installer and use the new version of python-build to build itself. That way, you would only need to run PYTHONPATH=path/to/python-installer makepkg to bootstrap python-build, rather than needing to provide both python-installer and python-build beforehand. After that, python-installer would build cleanly with just makepkg.

TL;DR: the makedepend on itself can be dropped if PYTHONPATH=src is added in build(). This doesn't fix bootstrapping newer Python versions out of the box completely, but makes it easier.

Additional info:

• package version(s): python 3.12.2-1, python-build 1.2.1-1 (built for python 3.11.8-1), python-installer 0.7.0-4 (built for python 3.11.8-1)
• config and/or log files: none relevant
• link to upstream bug report, if any: none, packaging issue

Steps to reproduce:

1. Have python be one minor version higher than the python used to build the installed python-build and python-installer
2. Attempt to run PYTHONPATH=path/to/python-installer makepkg in the python-build package directory
3. Observe error /usr/bin/python: No module named build