Update array2d.pyi

include/typings/array2d.pyi

@@ -18,7 +18,7 @@ class array2d(Generic[T]):
     def get(self, col: int, row: int, default=None): ...
 
     @overload
-    def __getitem__(self, index: tuple[int, int]): ...
+    def __getitem__(self, index: tuple[int, int]) -> T: ...
     @overload
     def __getitem__(self, index: tuple[slice, slice]) -> 'array2d[T]': ...
     @overload