Clean tests day3

src/day3.rs

@@ -135,11 +135,10 @@ fn build_full_path(
 #[cfg(test)]
 mod test {
     use super::*;
-    use std::io;
 
     #[test]
     fn test_input_parsing() {
-        let mut input = io::Cursor::new(b"U7,R6,D4,L4\n");
+        let mut input = "U7,R6,D4,L4\n".as_bytes();
         let expected = vec![Up(7), Right(6), Down(4), Left(4)];
 
         let res = parse_input(&mut input);