fix(deps): update dependency koa to v2.15.4 [security] (#220)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

code/koa/package.json

@@ -3,6 +3,6 @@
   "version": "0.0.1",
   "main": "index.js",
   "dependencies": {
-    "koa": "2.15.3"
+    "koa": "2.15.4"
   }
 }