Ignore coverage for clear_screen on windows.

src/imitation/util/util.py

@@ -473,6 +473,6 @@ def split_in_half(x: int) -> Tuple[int, int]:
 def clear_screen() -> None:
     """Clears the console screen."""
     if os.name == "nt":  # Windows
-        os.system("cls")
+        os.system("cls")  # pragma: no cover
     else:
         os.system("clear")