Remove an unused variable (#7)

Author: pkboom

Diff for: src/Builder.php

@@ -5,6 +5,7 @@
 use DateTime;
 use DateInterval;
 use BadMethodCallException;
+use Exception;
 use InvalidArgumentException;
 use Symfony\Component\Process\Process;
 
@@ -259,8 +260,8 @@ public function execute($command = null, callable $output = null)
             return $this->runProcess($this->process());
         }
 
-        return $this->retry($times, $sleep, function () use ($process) {
-            return $this->runProcess($process)->throw();
+        return $this->retry($times, $sleep, function ($attempts) {
+            return $this->runProcess($this->process())->throw();
         });
     }