build(deps): bump mongoose from 5.4.16 to 5.7.5 in /packages/server

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.4.16 to 5.7.5.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/History.md)
- [Commits](Automattic/mongoose@5.4.16...5.7.5)

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

packages/server/package.json

@@ -30,7 +30,7 @@
     "dotenv": "^6.2.0",
     "express": "^4.16.4",
     "express-session": "^1.15.6",
-    "mongoose": "^5.4.13",
+    "mongoose": "^5.7.5",
     "mongoose-findorcreate": "^3.0.0",
     "passport": "^0.4.0",
     "passport-oauth2-refresh": "^1.1.0",