Bump redis from 2.8.0 to 3.1.1

Bumps [redis](https://github.com/NodeRedis/node-redis) from 2.8.0 to 3.1.1.
- [Release notes](https://github.com/NodeRedis/node-redis/releases)
- [Changelog](https://github.com/NodeRedis/node-redis/blob/master/CHANGELOG.md)
- [Commits](redis/node-redis@v.2.8.0...v3.1.1)

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

Author: dependabot[bot]

package-lock.json

@@ -43,7 +43,7 @@
     "mocha": "^5.0.1",
     "moment": "^2.21.0",
     "node-fetch": "^2.6.1",
-    "redis": "^2.8.0",
+    "redis": "^3.1.1",
     "socket.io": "^2.0.4",
     "socket.io-client": "^2.0.4",
     "vue": "^2.5.13",