Update gallery drawer version (#15774)

diff --git a/examples/flutter_gallery/lib/gallery/drawer.dart b/examples/flutter_gallery/lib/gallery/drawer.dart
index 6c0b0be..d0a79ef 100644
--- a/examples/flutter_gallery/lib/gallery/drawer.dart
+++ b/examples/flutter_gallery/lib/gallery/drawer.dart
@@ -240,7 +240,7 @@
 
     final Widget aboutItem = new AboutListTile(
       icon: const FlutterLogo(),
-      applicationVersion: 'April 2017 Preview',
+      applicationVersion: 'March 2018 Preview',
       applicationIcon: const FlutterLogo(),
       applicationLegalese: '© 2017 The Chromium Authors',
       aboutBoxChildren: <Widget>[