update calendar selector to work with the latest octobercms versions

formwidgets/calendarselector/partials/_selector.htm

@@ -27,7 +27,7 @@
             <?php foreach ($calendars as $key=>$calendar): ?>
                 <tr>
                     <td class="list-checkbox nolink">
-                        <div class="checkbox custom-checkbox nolabel">
+                        <div class="checkbox nolabel">
                             <input id="checkbox_<?= $key ?>"
                                    type="checkbox"
                                    name="Settings[calendar_selector][<?= $key ?>][checked]"
@@ -69,4 +69,4 @@
     $("#checkboxAll").click(function () {
         $('input:checkbox').not(this).prop('checked', this.checked);
     });
-</script>
+</script>