Replace Py_NotImplemented returns with the macro form Py_RETURN_NOTIMPLEMENTED.
The macro was introduced in #12724.
diff --git a/Objects/methodobject.c b/Objects/methodobject.c
index f1a9f4b..a7334cf 100644
--- a/Objects/methodobject.c
+++ b/Objects/methodobject.c
@@ -208,8 +208,7 @@
         !PyCFunction_Check(self) ||
         !PyCFunction_Check(other))
     {
-        Py_INCREF(Py_NotImplemented);
-        return Py_NotImplemented;
+        Py_RETURN_NOTIMPLEMENTED;
     }
     a = (PyCFunctionObject *)self;
     b = (PyCFunctionObject *)other;