Make sure selecting the same file again raises 'change' again.

Without it, the event was fired on Firefox 128, but not on Chrome 129.

web/lindat-service/run.php

@@ -196,6 +196,7 @@ function saveTree() {
         reader.readAsText(file);
       }
     }
+    this.value = '';  // Make sure selecting the same file will fire 'change' handler again
   });
 
   jQuery(document).on('show.bs.tab', '#output_table_link', showTable);