Bump mailgun.js from 10.2.1 to 10.2.3 (#132)

Bumps [mailgun.js](https://github.com/mailgun/mailgun.js) from 10.2.1 to 10.2.3.
- [Release notes](https://github.com/mailgun/mailgun.js/releases)
- [Changelog](https://github.com/mailgun/mailgun.js/blob/master/CHANGELOG.md)
- [Commits](mailgun/mailgun.js@v10.2.1...v10.2.3)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Micha Preußer <[email protected]>

package.json

@@ -19,7 +19,7 @@
     "express-fileupload": "^1.5.0",
     "express-session": "^1.18.0",
     "html-to-text": "^9.0.5",
-    "mailgun.js": "^10.2.1",
+    "mailgun.js": "^10.2.3",
     "nodemailer": "^6.9.13",
     "mariadb": "^3.2.3",
     "pdfkit": "^0.15.0",