Bump koa from 3.0.3 to 3.1.1

Bumps [koa](https://github.com/koajs/koa) from 3.0.3 to 3.1.1.
- [Release notes](https://github.com/koajs/koa/releases)
- [Changelog](https://github.com/koajs/koa/blob/master/History.md)
- [Commits](koajs/koa@v3.0.3...v3.1.1)

---
updated-dependencies:
- dependency-name: koa
  dependency-version: 3.1.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

package-lock.json

@@ -22,7 +22,7 @@
     "handlebars": "^4.7.8",
     "http-errors": "^2.0.0",
     "http-graceful-shutdown": "^3.1.14",
-    "koa": "^3.0.3",
+    "koa": "^3.1.1",
     "koa-bodyparser": "^4.4.1",
     "koa-handlebars": "^2.0.0",
     "twitter-api-v2": "^1.24.0"