fix: package.json & package-lock.json to reduce vulnerabilities (#80)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-MQUERY-1089718

Co-authored-by: Christoph Werner <[email protected]>

Author: snyk-bot

package-lock.json

@@ -14,7 +14,7 @@
     "fast-json-patch": "^2.2.1",
     "humps": "^2.0.1",
     "lodash": "^4.17.21",
-    "mongoose": "^5.10.7"
+    "mongoose": "^5.12.3"
   },
   "devDependencies": {
     "babel-cli": "^6.26.0",