Python dependency failures on Raspberry Pi OS Bookworm

[cghague]

Related #1668

The TinyPilot Debian package fails to install on Raspberry Pi OS Bookworm with many errors relating to various missing Python dependencies, most noticeably flask and jinja2 (the latter of which causes the render-template script to fail).

We should investigate why this is and modify the Debian package to be compatible with Raspberry Pi OS Bookworm. A potential starting point for this task would be looking into why the workaround of changing the Debian package to create the Python venv at installation time rather than using a pre-packaged version works.

[RDGInfoSys]

Just as an FYI, using an "as of yesterday" (204-02-20) fresh install and update of 64-Bit Bullseye and an "as of the day before yesterday" (2024-02-19) fresh install and update of 64-Bit Bookworm, produce the same dependency errors for python3:

 tinypilot:armhf : Depends: python3:armhf but it is not going to be installed
                   Depends: python3-pip:armhf but it is not installable
                   Depends: python3-venv:armhf but it is not going to be installed