Allow unused imports for cargo test

src/bin/test-panic.rs

@@ -2,12 +2,12 @@
 #![feature(const_fn)]
 #![no_std]
 #![cfg_attr(not(test), no_main)]
+#![cfg_attr(test, allow(dead_code, unused_macros, unused_imports))]
 
 #[macro_use]
 extern crate blog_os;
 
 use blog_os::exit_qemu;
-#[cfg(not(test))]
 use core::panic::PanicInfo;
 
 #[cfg(not(test))]