Update dependency grunt to v1 [SECURITY]

Author: renovate[bot]

themes/landscape/package.json

@@ -3,7 +3,7 @@
   "version": "0.0.2",
   "private": true,
   "devDependencies": {
-    "grunt": "0.4.5",
+    "grunt": "1.5.3",
     "load-grunt-tasks": "0.2.1",
     "grunt-git": "0.2.14",
     "grunt-contrib-clean": "0.5.0",