chore(deps): bump nodemailer from 4.7.0 to 6.6.1 in /server

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 4.7.0 to 6.6.1.
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](nodemailer/nodemailer@v4.7.0...v6.6.1)

---
updated-dependencies:
- dependency-name: nodemailer
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

server/package-lock.json

@@ -21,6 +21,6 @@
     "body-parser": "^1.18.3",
     "express": "^4.16.4",
     "lodash": "^4.17.13",
-    "nodemailer": "^4.7.0"
+    "nodemailer": "^6.6.1"
   }
 }