Bump handlebars from 2.0.0 to 4.3.0 in /ui

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 2.0.0 to 4.3.0.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/wycats/handlebars.js/blob/master/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v2.0.0...v4.3.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

ui/package-lock.json

@@ -12,7 +12,7 @@
     "@ztree/ztree_v3": "3.5.40",
     "jquery": "1.11.1",
     "typeahead.js": "0.10.5",
-    "handlebars": "2.0.0",
+    "handlebars": "4.3.0",
     "x3dom": "1.7.0",
     "aframe-orbit-camera-component": "1.1.0"
   }