Improve stubs for sequence types (#6386)

stdlib/tracemalloc.pyi

@@ -1,6 +1,7 @@
 import sys
 from _tracemalloc import *
 from typing import Optional, Sequence, Tuple, Union, overload
+from typing_extensions import SupportsIndex
 
 def get_object_traceback(obj: object) -> Traceback | None: ...
 def take_snapshot() -> Snapshot: ...
@@ -63,7 +64,7 @@ class Traceback(Sequence[Frame]):
     else:
         def format(self, limit: int | None = ...) -> list[str]: ...
     @overload
-    def __getitem__(self, i: int) -> Frame: ...
+    def __getitem__(self, i: SupportsIndex) -> Frame: ...
     @overload
     def __getitem__(self, s: slice) -> Sequence[Frame]: ...
     def __len__(self) -> int: ...