Bump nodemailer from 6.4.12 to 6.4.13

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 6.4.12 to 6.4.13.
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](nodemailer/nodemailer@v6.4.12...v6.4.13)

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

package.json

@@ -21,7 +21,7 @@
     "mongoose": "5.9.29",
     "mongoose-lifecycle": "1.0.0",
     "node-hipchat": "0.4.5",
-    "nodemailer": "6.4.12",
+    "nodemailer": "6.4.13",
     "semver": "7.3.2",
     "socket.io": "^2.1.1",
     "spore": "0.1.6",