Bump mongoose from 5.8.11 to 5.9.1

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.8.11 to 5.9.1.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/History.md)
- [Commits](https://github.com/Automattic/mongoose/compare/5.8.11...5.9.1)

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

package.json

@@ -48,7 +48,7 @@
     "lodash": "^4.17.15",
     "marked": "^0.3.19",
     "moment": "^2.24.0",
-    "mongoose": "^5.7.5",
+    "mongoose": "^5.9.1",
     "nconf": "^0.10.0",
     "pico-router": "^2.1.0",
     "react": "^16.12.0",