zvariant: Maybe type is behind a gvariant feature flag
If zvariant is compiled without gvariant
feature, it currently fails with
error[E0432]: unresolved import `crate::Maybe`
--> /home/bilelmoussaoui/.cargo/git/checkouts/zbus-e0109d69954ffaa9/b338533/zvariant/src/owned_value.rs:5:22
|
5 | Array, Dict, Fd, Maybe, ObjectPath, OwnedObjectPath, OwnedSignature, Signature, Str, Structure,
| ^^^^^ no `Maybe` in the root