Bump js-yaml from 3.8.2 to 3.13.1 in /app

Bumps [js-yaml](https://github.com/nodeca/js-yaml) from 3.8.2 to 3.13.1.
- [Release notes](https://github.com/nodeca/js-yaml/releases)
- [Changelog](https://github.com/nodeca/js-yaml/blob/master/CHANGELOG.md)
- [Commits](https://github.com/nodeca/js-yaml/compare/3.8.2...3.13.1)

app/package.json

@@ -26,7 +26,7 @@
     "electron-debug": "^2.0.0",
     "electron-is-dev": "0.1.2",
     "electron-updater": "^4.0.6",
-    "js-yaml": "3.8.2",
+    "js-yaml": "3.13.1",
     "mz": "^2.6.0",
     "ngx-toastr": "^9.1.1",
     "path": "0.12.7",