message: fix: add touched on dropdown open
  fixes
diff: @@ -277,6 +277,7 @@ export class NgSelectComponent implements OnInit, OnDestroy, OnChanges, AfterVie
  this.itemsList.markSelectedOrDefault(this.markFirst);
  this._scrollToMarked();
  this._focusSearchInput();
  + this._onTouched();
  this.openEvent.emit();
  if (this.appendTo) {
  this._updateDropdownPosition();
  