Bump nodemailer from 3.1.8 to 6.4.16

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 3.1.8 to 6.4.16.
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](https://github.com/nodemailer/nodemailer/compare/v3.1.8...v6.4.16)
Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -21,7 +21,7 @@
     "koa-router": "next",
     "log4js": "^1.1.1",
     "mime": "^1.3.4",
-    "nodemailer": "^3.1.8",
+    "nodemailer": "^6.4.16",
     "pg": "^6.1.5",
     "typeorm": "^0.0.11",
     "uuid": "^3.0.1"