fix: package.json & package-lock.json to reduce vulnerabilities (#42)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-LODASH-450202

Author: snyk-bot

package-lock.json

@@ -8,7 +8,7 @@
     "dependencies": {
         "fast-json-patch": "^2.0.4",
         "humps": "^2.0.1",
-        "lodash": "^4.17.5",
+        "lodash": "^4.17.12",
         "mongoose": "^5.6.2"
     },
     "devDependencies": {