Convert observables to signals.

frontend/src/app/pages/home/home.component.html

@@ -1,10 +1,10 @@
 <h1 i18n>Last publications</h1>
 @if ((isLoading())) {
     <h2 i18n>Publications loading...</h2>
-    <mat-spinner></mat-spinner>
+    <mat-spinner />
 } @else {
     @if (publications(); as publications) {
-        <app-publication-list [publications]="publications"></app-publication-list>
+        <app-publication-list [publications]="publications" />
     } @else {
         <h2 i18n>No any publication.</h2>
     }