Bump nodemailer from 6.9.13 to 6.9.16 in /backend

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 6.9.13 to 6.9.16.
- [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/v6.9.13...v6.9.16)

---
updated-dependencies:
- dependency-name: nodemailer
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

backend/package.json

@@ -83,7 +83,7 @@
     "neo4j-graphql-js": "^2.11.5",
     "neode": "^0.4.9",
     "node-fetch": "^2.7.0",
-    "nodemailer": "^6.9.13",
+    "nodemailer": "^6.9.16",
     "nodemailer-html-to-text": "^3.2.0",
     "request": "~2.88.2",
     "sanitize-html": "~2.13.1",

backend/yarn.lock

@@ -7367,10 +7367,10 @@ nodemailer-html-to-text@^3.2.0:
   dependencies:
     html-to-text "7.1.1"
 
-nodemailer@^6.9.13:
-  version "6.9.13"
-  resolved "https://registry.yarnpkg.com/nodemailer/-/nodemailer-6.9.13.tgz#5b292bf1e92645f4852ca872c56a6ba6c4a3d3d6"
-  integrity sha512-7o38Yogx6krdoBf3jCAqnIN4oSQFx+fMa0I7dK1D+me9kBxx12D+/33wSb+fhOCtIxvYJ+4x4IMEhmhCKfAiOA==
+nodemailer@^6.9.16:
+  version "6.9.16"
+  resolved "https://registry.yarnpkg.com/nodemailer/-/nodemailer-6.9.16.tgz#3ebdf6c6f477c571c0facb0727b33892635e0b8b"
+  integrity sha512-psAuZdTIRN08HKVd/E8ObdV6NO7NTBY3KsC30F7M4H1OnmLCUNaS56FpYxyb26zWLSyYF9Ozch9KYHhHegsiOQ==
 
 nodemon@~3.1.7:
   version "3.1.7"