fix: fixed windows only test issue

src/exercise.rs

@@ -308,6 +308,7 @@ mod test {
                     path: PathBuf::from("tests/fixture/state/pending_exercise.rs"),
                     mode: *mode,
                     hint: String::from(""),
+                    next_path: None,
                 };
                 let _ = exercise.compile().unwrap();
                 assert!(!Path::new(&format!("{}.pdb", temp_file())).exists());