v0.6.3

A small release that:

• adapts isd to the recent textual changes,
• improves ansi themes,
• fixes journalctl output for user services without persistent storage,
• switched to Zensical from MkDocs Material, and
• updates the Python and nix dependencies.

With textual 8.2.5, upstream now provides ansi-dark and ansi-light themes that cover
the use case of the experimental terminal-derived-theme.
This release deprecates terminal-derived-theme in favor of those upstream themes.
Selecting the old theme still works, but isd now shows a warning notification pointing to the alternatives.

Full Changelog: v0.6.2...v0.6.3