fix: package.json & package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-REDIS-1255645

package-lock.json

@@ -5483,9 +5483,9 @@
       }
     },
     "redis": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/redis/-/redis-3.1.0.tgz",
-      "integrity": "sha512-//lAOcEtNIKk2ekZibes5oyWKYUVWMvMB71lyD/hS9KRePNkB7AU3nXGkArX6uDKEb2N23EyJBthAv6pagD0uw==",
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/redis/-/redis-3.1.1.tgz",
+      "integrity": "sha512-QhkKhOuzhogR1NDJfBD34TQJz2ZJwDhhIC6ZmvpftlmfYShHHQXjjNspAJ+Z2HH5NwSBVYBVganbiZ8bgFMHjg==",
       "requires": {
         "denque": "^1.5.0",
         "redis-commands": "^1.7.0",

package.json

@@ -14,7 +14,7 @@
     "ncp": "^2.0.0",
     "node-prismjs": "^0.1.0",
     "prismjs": "^1.23.0",
-    "redis": "^3.1.0",
+    "redis": "^3.1.1",
     "rss": "^1.2.2",
     "showdown": "^1.9.1"
   },