chore(deps): bump koa and @module-federation/enhanced in /shell-ui

Removes [koa](https://github.com/koajs/koa). It's no longer used after updating ancestor dependency [@module-federation/enhanced](https://github.com/module-federation/core/tree/HEAD/packages/enhanced). These dependencies need to be updated together.


Removes `koa`

Updates `@module-federation/enhanced` from 0.21.6 to 2.8.0
- [Release notes](https://github.com/module-federation/core/releases)
- [Changelog](https://github.com/module-federation/core/blob/main/packages/enhanced/CHANGELOG.md)
- [Commits](https://github.com/module-federation/core/commits/v2.8.0/packages/enhanced)

---
updated-dependencies:
- dependency-name: koa
  dependency-version:
  dependency-type: indirect
- dependency-name: "@module-federation/enhanced"
  dependency-version: 2.8.0
  dependency-type: direct:development
...

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Author: dependabot[bot]