Bump koa from 2.12.1 to 2.13.0

Bumps [koa](https://github.com/koajs/koa) from 2.12.1 to 2.13.0.
- [Release notes](https://github.com/koajs/koa/releases)
- [Changelog](https://github.com/koajs/koa/blob/master/History.md)
- [Commits](https://github.com/koajs/koa/compare/2.12.1...2.13.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -36,7 +36,7 @@
     "file-loader": "^6.0.0",
     "iso8601-duration": "^1.1.1",
     "kcors": "^2.2.1",
-    "koa": "^2.12.1",
+    "koa": "^2.13.0",
     "koa-bodyparser": "^4.3.0",
     "koa-compress": "~4.0.1",
     "koa-favicon": "~2.1.0",