Bump http-proxy-middleware and @vue/cli-service in /ui

Bumps [http-proxy-middleware](https://github.com/chimurai/http-proxy-middleware) to 2.0.7 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 `http-proxy-middleware` from 0.19.1 to 2.0.7
- [Release notes](https://github.com/chimurai/http-proxy-middleware/releases)
- [Changelog](https://github.com/chimurai/http-proxy-middleware/blob/v2.0.7/CHANGELOG.md)
- [Commits](https://github.com/chimurai/http-proxy-middleware/compare/v0.19.1...v2.0.7)

Updates `@vue/cli-service` from 3.6.0 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: http-proxy-middleware
  dependency-type: indirect
- dependency-name: "@vue/cli-service"
  dependency-type: direct:development
...

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

ui/package.json

@@ -39,7 +39,7 @@
     "@vue/cli-plugin-babel": "^3.3.0",
     "@vue/cli-plugin-eslint": "^3.3.0",
     "@vue/cli-plugin-unit-jest": "^3.3.0",
-    "@vue/cli-service": "^3.3.0",
+    "@vue/cli-service": "^5.0.8",
     "@vue/eslint-config-standard": "^4.0.0",
     "@vue/test-utils": "^1.0.0-beta.20",
     "babel-core": "7.0.0-bridge.0",