Update .gitlab-ci.yml

.gitlab-ci.yml

 image: php:7.2
 
-# Select what we should cache between builds
 cache:
   paths:
   - vendor/
 
 before_script:
-- docker-php-ext-install mbstring mcrypt pdo_pgsql curl json intl gd xml zip bz2 opcache
+- docker-php-ext-install mbstring pdo_pgsql curl json intl gd xml zip bz2 opcache
 - curl -sS https://getcomposer.org/installer | php
 - php composer.phar install
 - composer install --no-interaction --prefer-dist