prepared the 2.2.3 release

doc/changelog.rst

 Changelog
 =========
 
-2.2.3 (2018-XX-XX)
+2.2.3 (2018-02-25)
 ------------------
 
  * fixed validator integration into the security provider (order of registration of the validator and security providers does not matter anymore)

src/Silex/Application.php

@@ -41,7 +41,7 @@ use Silex\Provider\HttpKernelServiceProvider;
  */
 class Application extends Container implements HttpKernelInterface, TerminableInterface
 {
-    const VERSION = '2.2.3-DEV';
+    const VERSION = '2.2.3';
 
     const EARLY_EVENT = 512;
     const LATE_EVENT = -512;