build(deps): bump nth-check and @vue/cli-service in /demo/vue-cli4

Bumps [nth-check](https://github.com/fb55/nth-check) to 2.1.1 and updates ancestor dependency [@vue/cli-service](https://github.com/vuejs/vue-cli/tree/HEAD/packages/@vue/cli-service). These dependencies need to be updated together.


Updates `nth-check` from 1.0.2 to 2.1.1
- [Release notes](https://github.com/fb55/nth-check/releases)
- [Commits](fb55/nth-check@v1.0.2...v2.1.1)

Updates `@vue/cli-service` from 4.5.19 to 5.0.8
- [Release notes](https://github.com/vuejs/vue-cli/releases)
- [Changelog](https://github.com/vuejs/vue-cli/blob/dev/CHANGELOG.md)
- [Commits](https://github.com/vuejs/vue-cli/commits/v5.0.8/packages/@vue/cli-service)

---
updated-dependencies:
- dependency-name: nth-check
  dependency-type: indirect
- dependency-name: "@vue/cli-service"
  dependency-type: direct:development
...

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