sambacc: add version wrapper around typing.Self

Add version handling to typelets.py so that the sambacc code base can
use the Self type more freely, concentrating the version workarounds
in one place.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

sambacc/typelets.py

@@ -20,8 +20,17 @@
 """
 
 from types import TracebackType
+import sys
 import typing
 
 ExcType = typing.Optional[typing.Type[BaseException]]
 ExcValue = typing.Optional[BaseException]
 ExcTraceback = typing.Optional[TracebackType]
+
+
+if sys.version_info >= (3, 11):
+    from typing import Self
+elif typing.TYPE_CHECKING:
+    from typing_extensions import Self
+else:
+    Self = typing.Any