message: actions/drop: allow function as accept option
diff: @@ -131,7 +131,8 @@ function collectDrops ({ interactables }, draggableElement) {
  // test the draggable draggableElement against the dropzone's accept setting
  if ((utils.is.element(accept) && accept !== draggableElement)
  || (utils.is.string(accept)
  - && !utils.dom.matchesSelector(draggableElement, accept))) {
  + && !utils.dom.matchesSelector(draggableElement, accept))
  + || (utils.is.func(accept) && !accept({ dropzone, draggableElement }))) {
  continue;
  }
  @@ -139,7 +140,7 @@ function collectDrops ({ interactables }, draggableElement) {
  // query for new elements if necessary
  const dropElements = utils.is.string(dropzone.target)
  ? dropzone._context.querySelectorAll(dropzone.target)
  - : [dropzone.target];
  + : utils.is.array(dropzone.target) ? dropzone.target : [dropzone.target];
  for (const dropzoneElement of dropElements) {
  if (dropzoneElement !== draggableElement) {
  