Update @types/koa-router requirement from 7.0.39 to 7.0.40 (#4418)

Updates the requirements on [@types/koa-router](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/koa-router) to permit the latest version.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/koa-router

)

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