Update ProcessBuilder.php

Correctly escape ffmpeg shell command so that % symbol is not stripped out in case of multi-output.

Author: SamarRizvi

src/PHPVideoToolkit/ProcessBuilder.php

@@ -151,7 +151,7 @@ protected function _combineArgumentList($commands)
                 foreach ($commands as $argument)
                 {
                     // the array ois a flag for a raw argument
-                    $command_string .= (is_array($argument) === true ? $argument : escapeshellarg($argument)).' ';
+                    $command_string .= (is_array($argument) === true ? $argument : ProcessUtils::escapeArgument($argument)).' ';
                 }
             }