Reintroduce fixed Mongoose dependency

Author: tomgreenfield

package-lock.json

@@ -62,7 +62,7 @@
     "mime": "^2.4.4",
     "moment": "^2.24.0",
     "mongodb-uri": "^0.9.7",
-    "mongoose": "^5.9.18",
+    "mongoose": "5.8.13",
     "morgan": "^1.9.1",
     "multer": "^1.4.2",
     "needle": "^2.4.0",