fix: upgrade pg from 7.18.1 to 7.18.2

Snyk has created this PR to upgrade pg from 7.18.1 to 7.18.2.

See this package in NPM:
https://www.npmjs.com/package/pg

See this project in Snyk:
https://app.snyk.io/org/michaellperry/project/b842ff15-6f8d-4dde-910a-b659090b1b16?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -25,7 +25,7 @@
     "jsonwebtoken": "^8.5.1",
     "passport": "^0.4.1",
     "passport-twitter": "^1.0.4",
-    "pg": "^7.18.1",
+    "pg": "^7.18.2",
     "react": "^16.12.0",
     "react-dom": "^16.12.0",
     "source-map-support": "^0.5.16"