fix: adjust code to overcome the breaking changes (ionic 4 to 5)

Closes #70

src/app/modules/settings/page/settings-page.component.ts

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018, 2019 StApps
+ * Copyright (C) 2018, 2019, 2020 StApps
  * This program is free software: you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the Free
  * Software Foundation, version 3.
@@ -80,7 +80,7 @@ export class SettingsPageComponent {
    */
   private async presentSettingsResetToast() {
     const toast = await this.toastController.create({
-      cssClass: 'text-center',
+      cssClass: 'ion-text-center',
       duration: 2000,
       message: this.translateService.instant('settings.resetToast.message'),
     });