Bump koa from 2.14.2 to 2.15.0

Bumps [koa](https://github.com/koajs/koa) from 2.14.2 to 2.15.0.
- [Changelog](https://github.com/koajs/koa/blob/2.15.0/History.md)
- [Commits](koajs/koa@2.14.2...2.15.0)

---
updated-dependencies:
- dependency-name: koa
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -15,7 +15,7 @@
   },
   "dependencies": {
     "finished": "^1.2.2",
-    "koa": "^2.14.2",
+    "koa": "^2.15.0",
     "koa-body": "^6.0.1",
     "koa-router": "^12.0.1"
   },