Fix: usage of typing:Literal on sm_typing is added for obsolete Python.

Signed-off-by: Arnaud Garcia-Fernandez <arnaud.garcia-fernandez@vates.tech>

Author: Ythogtha

sm_typing/__init__.py

@@ -19,3 +19,6 @@ def override(method): # type: ignore
 
 if not hasattr(typing, 'Final'):
     Final = None # type: ignore
+
+if not hasattr(typing, "Literal"):
+    from typing_extensions import Literal  # noqa: F401, UP035