tkinter: Fix return type of winfo_children() (#14791)

Author: Akuli

stdlib/tkinter/__init__.pyi

@@ -460,7 +460,7 @@ class Misc:
     def winfo_atom(self, name: str, displayof: Literal[0] | Misc | None = 0) -> int: ...
     def winfo_atomname(self, id: int, displayof: Literal[0] | Misc | None = 0) -> str: ...
     def winfo_cells(self) -> int: ...
-    def winfo_children(self) -> list[Widget]: ...  # Widget because it can't be Toplevel or Tk
+    def winfo_children(self) -> list[Widget | Toplevel]: ...
     def winfo_class(self) -> str: ...
     def winfo_colormapfull(self) -> bool: ...
     def winfo_containing(self, rootX: int, rootY: int, displayof: Literal[0] | Misc | None = 0) -> Misc | None: ...