zv: Fix lifetime declarations in TryFrom<OwnedValue> impls
This fixes a bunch of warnings from clippy:
warning: this lifetime isn't used in the impl
--> zvariant/src/owned_value.rs:37:14
|
37 | impl<'a> TryFrom<OwnedValue> for $to {
| ^^
...
59 | ov_try_from!(u8);
| ---------------- in this macro invocation
|
= note: `#[warn(clippy::extra_unused_lifetimes)]` on by default
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
= note: this warning originates in the macro `ov_try_from` (in Nightly builds, run with -Z macro-backtrace for more info)