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] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -112,7 +112,7 @@
     "randomstring": "^1.1.5",
     "read-chunk": "^3.2.0",
     "recaptcha2": "^1.3.3",
-    "redis": "^2.8.0",
+    "redis": "^3.1.1",
     "request": "^2.88.0",
     "request-promise": "^4.2.4",
     "rss": "^1.2.2",