build(deps): bump loader-utils and @angular-devkit/build-angular

Bumps [loader-utils](https://github.com/webpack/loader-utils) to 3.2.1 and updates ancestor dependency [@angular-devkit/build-angular](https://github.com/angular/angular-cli). These dependencies need to be updated together.


Updates `loader-utils` from 1.2.3 to 3.2.1
- [Release notes](https://github.com/webpack/loader-utils/releases)
- [Changelog](https://github.com/webpack/loader-utils/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack/loader-utils/compare/v1.2.3...v3.2.1)

Updates `@angular-devkit/build-angular` from 0.803.20 to 15.0.0
- [Release notes](https://github.com/angular/angular-cli/releases)
- [Changelog](https://github.com/angular/angular-cli/blob/main/CHANGELOG.md)
- [Commits](https://github.com/angular/angular-cli/commits/15.0.0)

---
updated-dependencies:
- dependency-name: loader-utils
  dependency-type: indirect
- dependency-name: "@angular-devkit/build-angular"
  dependency-type: direct:development
...

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

openvidu-testapp/package.json

@@ -22,7 +22,7 @@
         "zone.js": "0.10.2"
     }, 
     "devDependencies": {
-        "@angular-devkit/build-angular": "0.803.20", 
+        "@angular-devkit/build-angular": "15.0.0", 
         "@angular/cli": "8.3.20", 
         "@angular/compiler-cli": "8.2.14", 
         "@angular/language-service": "8.2.14",