Added missing variable in the migration stub

Author: quentin.schmick

stubs/migration.stub

@@ -21,7 +21,7 @@ class {CLASS_NAME} extends Migration
             $table->string('field_name')->index();
             $table->string('field_value_old')->nullable()->index();
             $table->string('field_value_new')->nullable()->index();
-            $table->timestamp('occurred_at')->index();
+            $table->timestamp('occurred_at', {PRECISION})->index();
             $table->timestamps();
             {PROCESS_IDS_SETUP}