refactor(core): ignore the wrong_self_convention lint for CfgStartupHook::to_attr

Changing the receiver to `self` as per the suggestion complicates
the passing of this method to `ComptimeVec::map`, which expects
`~const FnMut(&CfgStartupHook)`. Converting `~const FnMut(CfgStartup-
Hook)` to `~const FnMut(&CfgStartupHook)` on-site is not trivial because
closures aren't callable in constant contexts yet.

Author: yvt

src/r3_core/src/kernel/hook.rs

@@ -154,6 +154,7 @@ impl Init for StartupHookAttr {
 }
 
 impl CfgStartupHook {
+    #[allow(clippy::wrong_self_convention)]
     pub const fn to_attr(&self) -> StartupHookAttr {
         StartupHookAttr { start: self.start }
     }