Closes #16294: 8 space indent in tutorial

Doc/tutorial/stdlib2.rst

@@ -257,9 +257,9 @@ applications include caching objects that are expensive to create::
    >>> import weakref, gc
    >>> class A:
    ...     def __init__(self, value):
-   ...             self.value = value
+   ...         self.value = value
    ...     def __repr__(self):
-   ...             return str(self.value)
+   ...         return str(self.value)
    ...
    >>> a = A(10)                   # create a reference
    >>> d = weakref.WeakValueDictionary()