Issue #3194401: Switch to CircleCI as the default automated testing platform

.circleci/config.yml

@@ -44,8 +44,11 @@ jobs:
       - run:
           name: Install PHP extra
           command: |
+            sudo -E docker-php-ext-install zip
             sudo -E docker-php-ext-configure pdo_mysql --with-pdo-mysql=mysqlnd
-            sudo -E docker-php-ext-install zip mbstring bcmath pdo pdo_mysql xml cgi cli common curl gd imap intl pspell sqlite3 tidy opcache json bz2 readline xmlrpc enchant xsl
+            sudo -E docker-php-ext-install bcmath pdo_mysql
+            sudo -E docker-php-ext-install gd
+            sudo -E docker-php-ext-install mbstring xml cgi cli common curl imap intl pspell sqlite3 tidy opcache json bz2 readline xmlrpc enchant xsl
             sudo service apache2 restart
 
       ## Change PHP Configurations.