🔖 zbus 4.2.1

• 🚑️ Critical fixes:
  • Don't invalidate all properties on change. This fixes a regression in c1aa5c7, where we
    started to invalidate properties in every PropertyChanged signal. This is wrong anyway but it
    also meant zbus interfaces breaking against gio. #765
  • Use assert! instead of debug_assert!. debug_assert! is removed in release builds, along
    with any values computed inside it. This meant that since the use of debug_assert! in
    commit 7fc3ab7, the fdo interfaces weren't getting added for
    nodes for release profile. Let's use assert! instead. #764
  • Fix 0 byte transfer and parsing regressions for FreeBSD. #756
• 💩 Hack to make connection handshake work inside Flatpak. xdg-dbus-proxy can't handle
  pipelining, hence we need to handle NEGOTIATE_UNIX_FD command's response before sending out
  BEGIN command and Hello method call message.
• 🥅 Gracefully handle rejection of UNIX FD passing.
• 🐛 Ensure all messsage bytes received during handshake are used. Don't assume that only a single
  full message could be received at the end of the client handshake process.
• 📝 Correct logo URL in docs.
• 🚨 Allow dead code in doc samples.
• ⬆️ Update dependencies:
  • serde to 1.0.200.
  • proc-macro2 to 1.0.81.
  • tokio to 1.37.0.