Add missing dashes to default argument

Co-authored-by: Wojciech Smoliński <[email protected]>

Author: schlessera

src/DB_Command.php

@@ -562,7 +562,7 @@ public function export( $args, $assoc_args ) {
 		}
 
 		if ( ! Utils\get_flag_value( $assoc_args, 'include-tablespaces', false ) ) {
-			$default_arguments[] = 'no-tablespaces';
+			$default_arguments[] = '--no-tablespaces';
 		}
 
 		$command = $initial_command . implode( ' ', $default_arguments );