reinstall socket.io

-{
-  "name": "project",
-  "version": "0.0.0",
-  "private": true,
-  "scripts": {
-    "start": "node ./bin/www"
-  },
-  "dependencies": {
-    "body-parser": "^1.18.3",
-    "compression": "^1.7.3",
-    "cookie-parser": "~1.4.3",
-    "date-utils": "^1.2.21",
-    "debug": "~2.6.9",
-    "ejs": "~2.5.7",
-    "express": "~4.16.0",
-    "helmet": "^3.21.2",
-    "http-errors": "~1.6.2",
-    "morgan": "~1.9.0",
-    "mysql": "^2.16.0",
-    "request": "^2.88.0",
-    "socket.io": "^2.1.1"
-  }
-}