🔖 zbus 4.3.1

• 💩 Workaround for xdg-dbus-proxy's monotonic serial requirement. While the underlying
  issue in xdg-dbus-proxy has already been fixed, it will take some time before the fix is
  released and is widely available.
• 🥅 Methods of interface-generated proxy now use the same error type as the interface's error
  type. We might need to add an attribute to control this in the future, as this as this may not
  always be what the user wants.
• 📝 book
  • Add a TOC to each chapter, using mdbook-toc from @badboy.
  • Add an FAQ section about enum representations.
  • Add property trait bounds to server chapter too.
  • Provide "edit page" option, making it easier to contribute fixes and improvements.
  • "server" -> "service". A D-Bus service is not a server, that's the bus. So let's keep these
    two distinct concepts separate.
  • Remove numeric labels from the navigation bar.
  • Update rust edition information.
  • Update repo icon to Github.
• ⬆️ Bump nix to v0.29.