🔖 zbus_names 2.6.0

• Simplify TryFrom<_> for BusName imps.
• Implement TryFrom<zvariant::Str> for all name types.
• Implement TryFrom<Cow<str>> for OwnedBusName.
• Implement From<_> for zvariant::Str.
• Bump our MSRV. More and more dependencies are requiring Rust 1.64.0, so let's bump our MSRV to
  match.