Prepare the 2.13.0 release

CHANGELOG

@@ -1,4 +1,4 @@
-# 2.13.0 (2020-XX-XX)
+# 2.13.0 (2020-07-05)
 
  * Fix options not taken into account when using "Michelf\MarkdownExtra"
  * Fix "Twig\Extra\Intl\IntlExtension::getCountryName()" to accept "null" as a first argument

src/Environment.php

@@ -38,12 +38,12 @@ use Twig\TokenParser\TokenParserInterface;
  */
 class Environment
 {
-    const VERSION = '2.13.0-DEV';
+    const VERSION = '2.13.0';
     const VERSION_ID = 21300;
     const MAJOR_VERSION = 2;
     const MINOR_VERSION = 13;
     const RELEASE_VERSION = 0;
-    const EXTRA_VERSION = 'DEV';
+    const EXTRA_VERSION = '';
 
     private $charset;
     private $loader;