Bump mongoose from 4.13.21 to 5.9.25

Bumps [mongoose](https://github.com/Automattic/mongoose) from 4.13.21 to 5.9.25.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/History.md)
- [Commits](Automattic/mongoose@4.13.21...5.9.25)

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

Author: dependabot[bot]

package.json

@@ -28,7 +28,7 @@
     "cookie-parser": "^1.4.1",
     "express": "^3.4.8",
     "express-session": "^1.13.0",
-    "mongoose": "^4.4.10",
+    "mongoose": "^5.9.25",
     "multer": "^1.1.0",
     "passport": "^0.3.2",
     "passport-local": "^1.0.0",