BPO-41085: Fixed 'array.array.index' downcasting 'Py_ssize_t' to 'long'.

Author: WildCard65

Modules/arraymodule.c

@@ -1130,7 +1130,7 @@ array_array_index(arrayobject *self, PyObject *v)
         cmp = PyObject_RichCompareBool(selfi, v, Py_EQ);
         Py_DECREF(selfi);
         if (cmp > 0) {
-            return PyLong_FromLong((long)i);
+            return PyLong_FromSsize_t(i);
         }
         else if (cmp < 0)
             return NULL;