[fix] results table migration

* update results table migration to avoid setting collation and character set on duration column

Author: jorgemudry

database/migrations/2019_09_25_103421_update_task_results_duration_type.php

@@ -1,7 +1,7 @@
 <?php
 
-use Illuminate\Support\Facades\Schema;
 use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
 use Studio\Totem\Database\TotemMigration;
 
 class UpdateTaskResultsDurationType extends TotemMigration
@@ -15,7 +15,7 @@ public function up()
     {
         Schema::connection(TOTEM_DATABASE_CONNECTION)
             ->table(TOTEM_TABLE_PREFIX.'task_results', function (Blueprint $table) {
-                $table->decimal('duration', 24, 14)->change();
+                $table->decimal('duration', 24, 14)->charset('')->collation('')->change();
             });
     }