Simplify imports in grammar.py

Author: aphedges

src/daidepp/grammar/grammar.py

@@ -7,11 +7,9 @@
 from typing import Dict, Tuple
 
 try:
-    from typing import Literal
-    from typing import get_args
+    from typing import Literal, get_args
 except ImportError:
-    from typing_extensions import Literal
-    from typing_extensions import get_args
+    from typing_extensions import Literal, get_args
 
 DAIDELevel = Literal[
     0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160