build(deps-dev): bump grunt-exec (#1856)

Author: dependabot[bot]

test-app/build-tools/android-metadata-generator/package.json

@@ -15,7 +15,7 @@
     "grunt": "0.4.5",
     "grunt-contrib-clean": "0.7.0",
     "grunt-contrib-copy": "0.8.2",
-    "grunt-exec": "0.4.6",
+    "grunt-exec": "0.4.7",
     "node-fs" : "0.1.7"
   }
 }