Show Workflow complete message after all steps are complete (#22)

Currently, this shows `Workflow complete.` after each _workflow step_
instead of after all the steps have completed.

src/Commands/Workflow.php

@@ -88,10 +88,10 @@ protected function execute( InputInterface $input, OutputInterface $output ) {
 			if ( $root ) {
 				chdir( $config->getWorkingDir() );
 			}
-
-			$io->writeln( '<success>Workflow complete.</success>' );
 		}
 
+		$io->writeln( '<success>Workflow complete.</success>' );
+
 		return 0;
 	}
 }