build(deps): bump loader-utils and @vue/cli-service in /demo/vue-cli3

Bumps [loader-utils](https://github.com/webpack/loader-utils) to 2.0.4 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 `loader-utils` from 0.2.17 to 2.0.4
- [Release notes](https://github.com/webpack/loader-utils/releases)
- [Changelog](https://github.com/webpack/loader-utils/blob/v2.0.4/CHANGELOG.md)
- [Commits](webpack/loader-utils@v0.2.17...v2.0.4)

Updates `@vue/cli-service` from 3.12.1 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: loader-utils
  dependency-type: indirect
- dependency-name: "@vue/cli-service"
  dependency-type: direct:development
...

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