qa: re-enable skipped test for class constant assertions

Signed-off-by: Maximilian Bösing <2189546+boesing@users.noreply.github.com>

tests/AssertAnnotationTest.php

@@ -1241,7 +1241,7 @@ function test($a, $b): string {
                         return substr($a, 0, 1) . substr($b, 0, 1);
                     }'
             ],
-            'SKIPPED-convertConstStringType' => [
+            'convertConstStringType' => [
                 '<?php
                     class A {
                         const T1 = 1;