🔖 zbus_xmlgen 5.0.0

• ⬆️ Upgrade dependencies:
  • zbus 5.0.0
  • zbus_xml 5.0.0
  • clap 4.5.4.
• ⬆️ Bump MSRV to 1.81.
• ➖ Remove direct dep on zvariant.
• 🩹 Set visibility of generated proxy to pub. This was the default visibility until proxy
  macro started to respect the visibility of the input trait. Let's set it to pub by default as
  that's what most folks will likely want. If not, they can easily modify it.