[ticket/10844] Increase prefix to not match template/ in finder test

PHPBB3-10844

tests/extension/finder_test.php

@@ -66,7 +66,7 @@ class phpbb_extension_finder_test extends phpbb_test_case
 	public function test_prefix_get_directories()
 	{
 		$dirs = $this->finder
-            ->prefix('t')
+            ->prefix('ty')
 			->get_directories();
 
 		sort($dirs);