Package version was not replaced here

Author: gsherwood

CodeSniffer/Reports/Checkstyle.php

@@ -114,7 +114,7 @@ public function generate(
         $toScreen=true
     ) {
         echo '<?xml version="1.0" encoding="UTF-8"?>'.PHP_EOL;
-        echo '<checkstyle version="@package_version@">'.PHP_EOL;
+        echo '<checkstyle version="'.PHP_CodeSniffer::VERSION.'">'.PHP_EOL;
         echo $cachedData;
         echo '</checkstyle>'.PHP_EOL;