e64f2a4be55b4c5b856df32b60f7cbbe1494caf8 Fix: Use "Black Right-Pointing Triangle" rather than "Black Right-Pointing Pointer" for child row display control

Sync to source repo @e64f2a4be55b4c5b856df32b60f7cbbe1494caf8

Author: AllanJard

css/dataTables.bootstrap4.css

@@ -19,7 +19,7 @@ table.dataTable td.dt-control {
 table.dataTable td.dt-control:before {
   display: inline-block;
   color: rgba(0, 0, 0, 0.5);
-  content: "►";
+  content: "▶";
 }
 table.dataTable tr.dt-hasChild td.dt-control:before {
   content: "▼";