Bump underscore from 1.12.1 to 1.13.0

Bumps [underscore](https://github.com/jashkenas/underscore) from 1.12.1 to 1.13.0.
- [Release notes](https://github.com/jashkenas/underscore/releases)
- [Commits](https://github.com/jashkenas/underscore/compare/1.12.1...1.13.0)

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

package.json

@@ -16,7 +16,7 @@
     "opensans-webkit": "^1.1.0",
     "popper.js": "^1.16.1",
     "sortablejs": "^1.13.0",
-    "underscore": "^1.12.1",
+    "underscore": "^1.13.0",
     "vis": "^4.21.0",
     "webpack-merge": "^5.7.3"
   },