hotfix(newsletter): newsletter button broken

src/app/newsletter-subscription/newsletter-subscription.component.html

@@ -23,7 +23,7 @@
         </div>
         <div class="button" fxLayout="row" fxLayoutAlign="space-around center">
           <a routerLink="../home" class="btn btn-link">Annuler</a>
-          <button type="button" [disabled]="loading" class="btn btn-primary">
+          <button type="submit" [disabled]="loading" class="btn btn-primary">
             <span *ngIf="loading" class="spinner-border spinner-border-sm mr-1"></span>
             <div *ngIf="subscriptionMod">S'inscrire</div>
             <div *ngIf="!subscriptionMod">Se désinscrire</div>