Fix --multiple option generating ZSH hook that resolves with the program ''

{$1} works under BASH, but doesn't resolve to anything under ZSH. Just
using $1 works correctly on both BASH and ZSH.

Author: stecman

src/HookFactory.php

@@ -132,7 +132,7 @@ public function generateHook($type, $programPath, $programName = null, $multiple
         $programName = $programName ?: $programPath;
 
         if ($multiple) {
-            $completionCommand = '${1} _completion';
+            $completionCommand = '$1 _completion';
         } else {
             $completionCommand = $programPath . ' _completion';
         }