[charm-dev] Install tox from pypi and other fixes

[sed-i]

In this PR:

• Tox from apt is quite dated. Install from PyPI instead. Fixes #43.
• Bump microk8s to 1.28. There is no strictly confined 1.29 at this point.
• Install bat, rg. These seem to have gained popularity.
• Update jhack installation.

[sed-i]

I assume you've tested this and works for the workflow you are trying to accomplish

Yep, cloud init completes successfully with a k8s and a lxd juju model bootstrapped and ready to use.