meson: Update syn subproject
What does this MR do and why?
meson: Update syn subproject
Fixes the following build error for fedora-release.
Error: method `inner` is never used
--> ../subprojects/syn-2.0.39/src/attr.rs:589:8
|
585 | pub(crate) trait FilterAttrs<'a> {
| ----------- method in this trait
...
589 | fn inner(self) -> Self::Ret;
| ^^^^^
|
= note: `-D dead-code` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(dead_code)]`
error: aborting due to 1 previous error
Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>