bumped version to 2.8.1-DEV

CHANGELOG

@@ -1,3 +1,7 @@
+* 2.8.1 (2019-XX-XX)
+
+ * n/a
+
 * 2.8.0 (2019-04-16)
 
  * added Traversable support for the length filter

src/Environment.php

@@ -38,12 +38,12 @@ use Twig\TokenParser\TokenParserInterface;
  */
 class Environment
 {
-    const VERSION = '2.8.0';
-    const VERSION_ID = 20800;
+    const VERSION = '2.8.1-DEV';
+    const VERSION_ID = 20801;
     const MAJOR_VERSION = 2;
     const MINOR_VERSION = 8;
-    const RELEASE_VERSION = 0;
-    const EXTRA_VERSION = '';
+    const RELEASE_VERSION = 1;
+    const EXTRA_VERSION = 'DEV';
 
     private $charset;
     private $loader;