prepared the 2.7.1 release

CHANGELOG

@@ -1,4 +1,4 @@
-* 2.7.1 (2019-XX-XX)
+* 2.7.1 (2019-03-12)
 
  * fixed class aliases
 

src/Environment.php

@@ -38,12 +38,12 @@ use Twig\TokenParser\TokenParserInterface;
  */
 class Environment
 {
-    const VERSION = '2.7.1-DEV';
+    const VERSION = '2.7.1';
     const VERSION_ID = 20701;
     const MAJOR_VERSION = 2;
     const MINOR_VERSION = 7;
     const RELEASE_VERSION = 1;
-    const EXTRA_VERSION = 'DEV';
+    const EXTRA_VERSION = '';
 
     private $charset;
     private $loader;