Between Debian 11 and 12 the way to install Python packages into the
system location under /usr, and not /usr/local, changed[1].  The
previous setup argument --install-layout=deb is now unsupported and the
environment variable DEB_PYTHON_INSTALL_LAYOUT needs to be set instead.

See also [2].

[1]: https://lists.debian.org/debian-devel/2023/07/msg00307.html
[2]: https://salsa.debian.org/selinux-team/libselinux/-/commit/cbfb31a0925e01591a9cce1eb3a0e517f42b144c

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>