update ss58 type to u16 (#8955)

substrate/bin/node/runtime/src/lib.rs

@@ -186,7 +186,7 @@ parameter_types! {
 		})
 		.avg_block_initialization(AVERAGE_ON_INITIALIZE_RATIO)
 		.build_or_panic();
-	pub const SS58Prefix: u8 = 42;
+	pub const SS58Prefix: u16 = 42;
 }
 
 const_assert!(NORMAL_DISPATCH_RATIO.deconstruct() >= AVERAGE_ON_INITIALIZE_RATIO.deconstruct());