fix(deps): update dependency koa to v2.15.3

Author: renovate[bot]

code/koa/package.json

@@ -3,6 +3,6 @@
   "version": "0.0.1",
   "main": "index.js",
   "dependencies": {
-    "koa": "2.14.2"
+    "koa": "2.15.3"
   }
 }