Add GitLab CI

• Different set of boxes, there isn't a 7.2 in the current series and doesn't seem like that'll changes
• Correct PHPUnit version for PHP version, as Travis handles

Fixes #2 (closed)

.gitlab-ci.yml

@@ -11,7 +11,7 @@ before_script:
   - apt-get -yqq update
 
   # install the required packages for the running CI tests
-  - apt-get -yqqf install zip unzip subversion mysql-client default-libmysqlclient-dev --fix-missing
+  - apt-get -yqqf install zip unzip subversion mysql-client --fix-missing
 
   # PHP extensions
   - docker-php-ext-install mbstring