Fixed #[panic_handler] for cfg(test)

mission_rust/src/panic.rs

@@ -5,6 +5,7 @@ extern "C" {
     fn done();
 }
 
+#[cfg(not(test))]
 #[panic_handler]
 fn panic(panic: &PanicInfo<'_>) -> ! {
     // unsafe { this breaks in ISR