[3.13] Fix documentation of hash in PyHash_FuncDef (GH-137595) (#137643)

Fix documentation of hash in PyHash_FuncDef (GH-137595)

Because of a small typo, it wasn't showing up in the generated docs.
(cherry picked from commit 70218b4)

Co-authored-by: da-woods <[email protected]>

Author: miss-islington

Doc/c-api/hash.rst

@@ -51,7 +51,7 @@ See also the :c:member:`PyTypeObject.tp_hash` member and :ref:`numeric-hash`.
 
    Hash function definition used by :c:func:`PyHash_GetFuncDef`.
 
-   .. c::member:: Py_hash_t (*const hash)(const void *, Py_ssize_t)
+   .. c:member:: Py_hash_t (*const hash)(const void *, Py_ssize_t)
 
       Hash function.