refactor(proto): use derive macro to implement Default for KA

Author: tottoto

src/proto/h1/conn.rs

@@ -903,19 +903,14 @@ impl std::ops::BitAndAssign<bool> for KA {
     }
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, Default)]
 enum KA {
     Idle,
+    #[default]
     Busy,
     Disabled,
 }
 
-impl Default for KA {
-    fn default() -> KA {
-        KA::Busy
-    }
-}
-
 impl KA {
     fn idle(&mut self) {
         *self = KA::Idle;