🐛 zv: Do not derive Eq for Signature

As per [`Eq`](https://doc.rust-lang.org/stable/std/cmp/trait.Eq.html#derivable)
docs on deriving: "Note that the derive strategy requires all fields are `Eq,
 which isn’t always desired."

We specify conditional `Signature` equality that does not include all
fields are (derivable) `Eq`.

This is why `Eq` for `Signature` is manually implemented.

zvariant/src/signature.rs

@@ -96,7 +96,7 @@ impl<'b> std::ops::Deref for Bytes<'b> {
 ///
 /// [identifies]: https://dbus.freedesktop.org/doc/dbus-specification.html#type-system
 /// [`slice`]: #method.slice
-#[derive(Eq, Hash, Clone)]
+#[derive(Hash, Clone)]
 pub struct Signature<'a> {
     bytes: Bytes<'a>,
     pos: usize,
@@ -445,6 +445,10 @@ impl<'a> PartialEq<&str> for Signature<'a> {
     }
 }
 
+// According to the docs, `Eq` derive should only be used on structs if all its fields are
+// are `Eq`. Hence the manual implementation.
+impl Eq for Signature<'_> {}
+
 impl<'a> Display for Signature<'a> {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         std::fmt::Display::fmt(&self.as_str(), f)