title: Laradock changing php-fpm version inside workspace
body: <p>I am not able to change the php-fpm version inside the workspace. I'm trying to install PHP version 7.1
  My docker version is</p>
  
  <pre><code> Docker version 18.06.1-ce, build e68fc7a
  </code></pre>
  
  <p>Every time it installs PHP version </p>
  
  <pre><code>PHP 7.2.4-1+ubuntu16.04.1+deb.sury.org+1 (cli) (built: Apr  5 2018 08:53:57) ( NTS )
  </code></pre>
  
  <p>My dockerfile inside workspace looks like as follows:</p>
  
  <pre><code>ARG LARADOCK_PHP_VERSION=7.1
  
  FROM laradock/workspace:2.2-${LARADOCK_PHP_VERSION}
  
  LABEL maintainer="Mahmoud Zalt &lt;mahmoud@zalt.me&gt;"
  
  ARG LARADOCK_PHP_VERSION
  
  # Set Environment Variables
  ENV DEBIAN_FRONTEND noninteractive
  
  # Start as root
  USER root
  
  ###########################################################################
  # Laradock non-root user:
  ###########################################################################
  
  # Add a non-root user to prevent files being created with root permissions on host machine.
  ARG PUID=1000
  ENV PUID ${PUID}
  ARG PGID=1000
  ENV PGID ${PGID}
  </code></pre>