chore(devdeps): update dependency koa to v2.10.0

Author: renovate-bot

package-lock.json

@@ -40,7 +40,7 @@
     "eslint-config-standard-tunnckocore": "1.0.10",
     "hela": "2.0.10",
     "husky": "3.0.8",
-    "koa": "2.8.2",
+    "koa": "2.10.0",
     "semantic-release": "^7.0.0",
     "supertest": "4.0.2"
   },