Update mathcat_test.php

tests/mathcat_test.php

@@ -150,7 +150,7 @@ public static function conversion_of_array_to_vector_provider(): array {
             'modified and reordered' => [
                 'given' => [0, 'first' => 2, 'second' => [7, 9, 8], 'third' => 5],
                 'expected' => [0 => 0.0, 'first' => 2.0, 'second' => [1 => 7.0, 3 => 9.0, 2 => 8.0], 'third' => 5.0],
-                'structure' => [0 => 0, 'first' => 1, 'second' => [0 => 2, 1 => 4, 2 => 3], 'third' => 5],
+                'structure' => [0 => 0, 'first' => 1, 'second' => [0 => 2, 1 => 3, 2 => 4], 'third' => 5],
             ],
 
             // Forbidden cases: strings in array, empty arrays.