bpo-37432: Doc: Fix signature of PyObject_Del() (GH-14430)

diff --git a/Doc/c-api/allocation.rst b/Doc/c-api/allocation.rst
index 8e8a920..33b0c06 100644
--- a/Doc/c-api/allocation.rst
+++ b/Doc/c-api/allocation.rst
@@ -48,7 +48,7 @@
    improving the memory management efficiency.
 
 
-.. c:function:: void PyObject_Del(PyObject *op)
+.. c:function:: void PyObject_Del(void *op)
 
    Releases memory allocated to an object using :c:func:`PyObject_New` or
    :c:func:`PyObject_NewVar`.  This is normally called from the