Update Super Tux Kart egg

[Vorkal]

Description

When running the current SuperTuxKart egg, this message prevents dependencies from installing properly

E: The repository 'http://deb.debian.org/debian bullseye-backports Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.

This Pull Request resolves the issue by changing the repository to bookworm-backports and adjusts directory check logic to better handle interrupted installations.

JSON meta version updated from PTDL_v2 to PLCN_V3

Changes

Updated Debian repository: Updated install script to use bookworm-backports instead of bullseye-backports.
Adjusted directory path check: Changed && to || in the directory existence check to better handle partial/failed installations

Checklist for all submissions

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you tested and reviewed your changes with confidence that everything works?
• Did you branch your changes and PR from that branch and not from your master branch?
  • If not, why?:

• You verify that the start command applied does not use a shell script
  • If some script is needed then it is part of a current yolk or a PR to add one
• The egg was exported from the panel