Removed bashism in Dockerfile
Removed bashism in Dockerfile

andrerom/php,thaJeztah/php,ffhenkes/php,jabrankhalil/php,docker-library/php,junxy/docker-php,longmonhau/php,liukaitj/php,iwat/docker-library-php,liukaitj/php,dsingleton47/php,nishantmshah/php,razorpay/docker_php,NUOCW/docker-php,SSW-SCIENTIFIC/docker-php,tsilenzio/docker-php,snowair/php-docker,skyred/docker-php,rashpile/php,frlaugier/php,infosiftr/php,NoUseFreak/php,DoveConviene/php,primowebsolutions/php,ezmac/php