Build: Bump handlebars from 4.7.6 to 4.7.7

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.7.6 to 4.7.7.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/handlebars-lang/handlebars.js/blob/master/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v4.7.6...v4.7.7)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Closes gh-575

Author: dependabot[bot]

package-lock.json

@@ -24,7 +24,7 @@
     "grunt-contrib-handlebars": "2.0.0",
     "grunt-contrib-jshint": "2.1.0",
     "grunt-contrib-uglify": "5.0.0",
-    "handlebars": "4.7.6",
+    "handlebars": "4.7.7",
     "jquery-ui-themeroller": "0.0.5",
     "lzma": "2.3.2",
     "node-packager": "0.0.6",