Upgrade angular from 20 to 21.

frontend/src/main.ts

@@ -1,8 +1,9 @@
+import { provideZoneChangeDetection } from "@angular/core";
 /// <reference types="@angular/localize" />
 
 import { bootstrapApplication } from '@angular/platform-browser';
 import { appConfig } from './app/app.config';
 import { AppComponent } from './app/app.component';
 
-bootstrapApplication(AppComponent, appConfig)
+bootstrapApplication(AppComponent, {...appConfig, providers: [provideZoneChangeDetection(), ...appConfig.providers]})
   .catch((err) => console.error(err));