fix: docs/themes/docdock/static/revealjs/plugin/multiplex/package.json to reduce vulnerabilities (#698)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-LODASH-590103

Author: snyk-bot

docs/themes/docdock/static/revealjs/plugin/multiplex/package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "express": "~4.13.3",
-    "grunt-cli": "~0.1.13",
+    "grunt-cli": "~1.3.0",
     "mustache": "~2.2.1",
     "socket.io": "~1.3.7"
   },