feat(nx): upgrade nx 20 and angular 19

apps/testing/23-harness/src/app/app.component.ts

@@ -2,7 +2,6 @@ import { Component } from '@angular/core';
 import { ChildComponent } from './child.component';
 
 @Component({
-  standalone: true,
   imports: [ChildComponent],
   selector: 'app-root',
   template: `

apps/testing/23-harness/src/app/child.component.ts

@@ -86,7 +86,6 @@ import { MatSliderModule } from '@angular/material/slider';
       }
     `,
   ],
-  standalone: true,
   imports: [
     MatCardModule,
     MatFormFieldModule,

apps/testing/23-harness/src/styles.scss

@@ -6,7 +6,8 @@
 
 /* You can add global styles to this file, and also import other style files */
 
-@include mat.core();
+@include mat.elevation-classes();
+@include mat.app-background();
 
 $theme-primary: mat.m2-define-palette(mat.$m2-indigo-palette);
 $theme-accent: mat.m2-define-palette(mat.$m2-pink-palette, A200, A100, A400);