Update version number, add hint of which version it is

Author: André R

lib/version.php

@@ -15,10 +15,10 @@
 class eZPublishSDK
 {
     const VERSION_MAJOR = 5;
-    const VERSION_MINOR = 90;
-    const VERSION_RELEASE = 0;
-    const VERSION_STATE = 'alpha1';
-    const VERSION_DEVELOPMENT = true;
+    const VERSION_MINOR = 97;
+    const VERSION_RELEASE = 12;
+    const VERSION_STATE = '';
+    const VERSION_DEVELOPMENT = false;
     const VERSION_ALIAS = '2017.12';
     const EDITION = 'eZ Publish legacy';