fix(deps, frontend): update dependency @angular/core to v21.2.20 - #8494

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-go@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Restore cache failed: Some specified paths were not resolved, unable to cache dependencies.