chore(back/AuthToken): update to new AuthProof use method from swaf

src/models/AuthToken.ts

@@ -35,11 +35,9 @@ export default class AuthToken extends Model implements AuthProof<User> {
         }
     }
 
-    /**
-     * TODO promote this method to AuthProof interface in swaf and call it on successful authentication
-     */
-    public use(): void {
+    public async use(): Promise<void> {
         this.used_at = new Date();
+        await this.save();
     }
 
     public canDelete(user_id: number): boolean {