fix test for new bitsy version

src/sprite.rs

@@ -133,7 +133,8 @@ mod test {
 
     #[test]
     fn test_sprite_from_string() {
-        let output = Sprite::from(include_str!("test-resources/sprite").to_string()).unwrap();
+        let string = include_str!("test-resources/sprite").to_string();
+        let output = Sprite::from(string).unwrap();
         let expected = mock::sprite();
 
         assert_eq!(output, expected);