Bump koa from 2.15.3 to 2.15.4

Bumps [koa](https://github.com/koajs/koa) from 2.15.3 to 2.15.4.
- [Release notes](https://github.com/koajs/koa/releases)
- [Changelog](https://github.com/koajs/koa/blob/2.15.4/History.md)
- [Commits](koajs/koa@2.15.3...2.15.4)

---
updated-dependencies:
- dependency-name: koa
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package-lock.json

@@ -21,7 +21,7 @@
     "handlebars": "^4.7.8",
     "http-errors": "^2.0.0",
     "http-graceful-shutdown": "^3.1.14",
-    "koa": "^2.15.3",
+    "koa": "^2.15.4",
     "koa-bodyparser": "^4.4.1",
     "koa-handlebars": "^2.0.0",
     "twitter-api-v2": "^1.19.0"