Update expenses.civix.php

Deprecated: Array and string offset access syntax with curly braces is deprecated

expenses.civix.php

@@ -244,7 +244,7 @@ function _expenses_civix_find_files($dir, $pattern) {
     if ($dh = opendir($subdir)) {
       while (FALSE !== ($entry = readdir($dh))) {
         $path = $subdir . DIRECTORY_SEPARATOR . $entry;
-        if ($entry{0} == '.') {
+        if ($entry[0] == '.') {
         }
         elseif (is_dir($path)) {
           $todos[] = $path;