bpo-43928: Fix 'succesfully' typo in document (GH-25569)

Author: jeffreytse

Doc/c-api/memory.rst

@@ -306,7 +306,7 @@ memory from the Python heap.
 
 .. note::
     There is no guarantee that the memory returned by these allocators can be
-    succesfully casted to a Python object when intercepting the allocating
+    successfully casted to a Python object when intercepting the allocating
     functions in this domain by the methods described in
     the :ref:`Customize Memory Allocators <customize-memory-allocators>` section.