fix: package.json & package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-BL-608877
- https://snyk.io/vuln/SNYK-JS-SEMVER-3247795

package.json

@@ -35,7 +35,7 @@
     "marked": "0.3.5",
     "method-override": "latest",
     "moment": "2.15.1",
-    "mongodb": "^3.5.9",
+    "mongodb": "^3.6.6",
     "mongoose": "5.13.20",
     "morgan": "latest",
     "ms": "^0.7.1",