refactor(yang): remove unused Optional import from paths

The `Optional` type was imported from `typing` in `src/yang/paths.py`
but was not being used in the file. This change removes the unnecessary
import to clean up the code.

src/yang/paths.py

@@ -15,7 +15,6 @@ Usage:
 """
 
 from dataclasses import dataclass
-from typing import Optional
 
 
 # =============================================================================