[Security] 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. **This update includes a security fix.**
- [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-preview[bot] <support@dependabot.com>

package.json

@@ -53,7 +53,7 @@
     "debounce": "^1.2.0",
     "dompurify": "^2.2.6",
     "escape-html": "^1.0.3",
-    "handlebars": "^4.7.6",
+    "handlebars": "^4.7.7",
     "jcrop": "git+https://github.com/ChristophWurst/Jcrop.git#v0.9.12-npm3",
     "jquery": "~3.3",
     "jquery-migrate": "~3.3",