fix kopieer gebruikersnamen button (#1000)

Author: lodewiges

app/components/form/responses-table-card.hbs

@@ -4,7 +4,7 @@
       <div class='row align-items-center'>
         <h5 class='card-title col'>Inschrijvingen</h5>
         <div class='col col-md-auto d-flex align-items-center flex-wrap'>
-          <button class='btn btn-primary btn-sm me-3 my-2 text-nowrap' type="button" {{on 'click' this.copyUsernames}}>
+          <button class='btn btn-primary btn-sm me-3 my-2 text-nowrap' type="button" {{on 'click' (action 'copyUsernames')}}>
             Kopieer gebruikersnamen
           </button>
           <div class="form-check">