chore(package): update koop to version 3.6.1

Closes #17

Author: greenkeeper[bot]

package.json

@@ -14,7 +14,7 @@
     "request": "^2.65.0"
   },
   "devDependencies": {
-    "koop": "2.12.1",
+    "koop": "3.6.1",
     "standard": "^9.0.1",
     "supertest": "^3.0.0",
     "tap-spec": "^4.0.2",