Bump mongoose from 5.5.9 to 5.13.15

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.5.9 to 5.13.15.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/CHANGELOG.md)
- [Commits](https://github.com/Automattic/mongoose/compare/5.5.9...5.13.15)

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

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

package.json

@@ -16,6 +16,6 @@
     "bcrypt": "^5.0.0",
     "body-parser": "^1.19.0",
     "express": "^4.16.4",
-    "mongoose": "^5.5.9"
+    "mongoose": "^5.13.15"
   }
 }