fix: package.json & package-lock.json to reduce vulnerabilities (#96)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-SOCKETIO-1024859

Author: snyk-bot

package-lock.json

@@ -49,7 +49,7 @@
     "prepper": "^1.2.0",
     "ramda": "^0.27.0",
     "require-all": "^3.0.0",
-    "socket.io": "^2.3.0",
+    "socket.io": "^2.4.0",
     "socket.io-client": "^2.3.0",
     "systemic": "^3.3.7",
     "systemic-domain-runner": "^1.1.0",