[player] Fix wrong font for content of alert dialog

projects/player/src/app/components/alert-dialog/alert-dialog.component.html

 <h2 mat-dialog-title>{{data.title}}</h2>
-<mat-dialog-content>{{data.content}}</mat-dialog-content>
+<mat-dialog-content class="mat-typography">
+  <p>{{data.content}}</p>
+</mat-dialog-content>
 <mat-dialog-actions>
   <button mat-button mat-dialog-close>{{'close' | translate}}</button>
 </mat-dialog-actions>