chore(deps): bump koa and @types/koa (#6524)

Bumps [koa](https://github.com/koajs/koa) and [@types/koa](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/koa). These dependencies needed to be updated together.

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

Updates `@types/koa` from 2.13.6 to 2.14.0
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/koa)

---
updated-dependencies:
- dependency-name: koa
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: "@types/koa"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -125,7 +125,7 @@
     "jszip": "^3.10.1",
     "katex": "^0.16.9",
     "kbar": "0.1.0-beta.41",
-    "koa": "^2.14.2",
+    "koa": "^2.15.0",
     "koa-body": "^6.0.1",
     "koa-compress": "^5.1.1",
     "koa-helmet": "^6.1.0",
@@ -258,7 +258,7 @@
     "@types/jest": "^29.4.0",
     "@types/jsonwebtoken": "^8.5.9",
     "@types/katex": "^0.16.0",
-    "@types/koa": "^2.13.6",
+    "@types/koa": "^2.14.0",
     "@types/koa-compress": "^4.0.6",
     "@types/koa-helmet": "^6.0.8",
     "@types/koa-logger": "^3.1.5",