Add @final to many unsubclassable stdlib classes (#6299)

stdlib/_tkinter.pyi

@@ -1,5 +1,5 @@
 from typing import Any
-from typing_extensions import Literal
+from typing_extensions import Literal, final
 
 # _tkinter is meant to be only used internally by tkinter, but some tkinter
 # functions e.g. return _tkinter.Tcl_Obj objects. Tcl_Obj represents a Tcl
@@ -14,6 +14,7 @@ from typing_extensions import Literal
 #    >>> text.tag_add('foo', '1.0', 'end')
 #    >>> text.tag_ranges('foo')
 #    (<textindex object: '1.0'>, <textindex object: '2.0'>)
+@final
 class Tcl_Obj:
     string: str  # str(tclobj) returns this
     typename: str
@@ -37,6 +38,7 @@ class TclError(Exception): ...
 #
 # eval always returns str because _tkinter_tkapp_eval_impl in _tkinter.c calls
 # Tkapp_UnicodeResult, and it returns a string when it succeeds.
+@final
 class TkappType:
     # Please keep in sync with tkinter.Tk
     def call(self, __command: Any, *args: Any) -> Any: ...