build(deps): 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] <support@github.com>

packages/backend/package.json

@@ -65,7 +65,7 @@
     "fs-extra": "^11.2.0",
     "i18next": "^23.11.5",
     "inversify": "^6.0.2",
-    "koa": "^2.15.3",
+    "koa": "^2.15.4",
     "koa-bodyparser": "^4.4.1",
     "koa-send": "^5.0.1",
     "koa-static": "^5.0.0",