_tcl: fix bytes usage (#9010)

Author: JelleZijlstra

stdlib/_tkinter.pyi

@@ -17,8 +17,10 @@ from typing_extensions import Literal, final
 #    (<textindex object: '1.0'>, <textindex object: '2.0'>)
 @final
 class Tcl_Obj:
-    string: str | bytes
-    typename: str
+    @property
+    def string(self) -> str: ...
+    @property
+    def typename(self) -> str: ...
     __hash__: ClassVar[None]  # type: ignore[assignment]
     def __eq__(self, __other): ...
     def __ge__(self, __other): ...