fix: apprise install after bookworm update

[k3rnelpan1c-dev]

This PR aims to fix the Apprise install after the move to Bookworm (Debian 12).
With Debian 12 comes Python 3.11 and PEP-668, which means that installing Debian's Python system package has the "externally managed environments" set.

There are basically 2 paths to circumvent this causing errors:

• utilise pip's --break-system-packages flag (keeps the old behaviour how I installed apprise)
• use a venv as PEP-668 intents to nag you to do.

I attempted the latter, however, since I never really worked with venv nor claim to be a python crack in general I was unable to get it to work within the limited time I had available to invest in this update.
Similarly, I had no luck with attempting to use pipx, which abstracts away the venv for you, but then fails to make apprise available system wide.
Finally, I opted to use the --break-system-packages flag, as the impact of installing apprise is foreseeable and we live within a container anyway.

If anyone finds this PR and wants to contribute a pipx solution I would be interested, but in the mean time this will do.