Bump webpack and @angular-devkit/build-angular in /samples/spa-client

Bumps [webpack](https://github.com/webpack/webpack) to 5.105.0 and updates ancestor dependency [@angular-devkit/build-angular](https://github.com/angular/angular-cli). These dependencies need to be updated together.


Updates `webpack` from 5.94.0 to 5.105.0
- [Release notes](https://github.com/webpack/webpack/releases)
- [Changelog](https://github.com/webpack/webpack/blob/main/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack/compare/v5.94.0...v5.105.0)

Updates `@angular-devkit/build-angular` from 18.2.11 to 21.1.3
- [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/compare/18.2.11...v21.1.3)

---
updated-dependencies:
- dependency-name: webpack
  dependency-version: 5.105.0
  dependency-type: indirect
- dependency-name: "@angular-devkit/build-angular"
  dependency-version: 21.1.3
  dependency-type: direct:development
...

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

samples/spa-client/package.json

@@ -23,7 +23,7 @@
     "zone.js": "~0.14.10"
   },
   "devDependencies": {
-    "@angular-devkit/build-angular": "^18.2.11",
+    "@angular-devkit/build-angular": "^21.1.3",
     "@angular/cli": "^18.2.11",
     "@angular/compiler-cli": "^18.2.0",
     "@types/jasmine": "~5.1.0",