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

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-NODEMAILER-1038834

Author: snyk-bot

package-lock.json

@@ -37,7 +37,7 @@
     "jsonwebtoken": "^8.5.1",
     "marked": "^1.1.1",
     "mongoose": "^5.9.27",
-    "nodemailer": "^6.4.10",
+    "nodemailer": "^6.4.16",
     "pino": "^6.5.0",
     "pngquant": "^3.1.0",
     "reflect-metadata": "^0.1.13",