Revert to the base FPFIS images.

We no longer need to use the experimental Ubuntu images since these
have been merged into the base images recently.

Author: pfrenssen

.drone.yml

@@ -54,8 +54,8 @@ pipeline:
 
 matrix:
   IMAGE_PHP:
-    - fpfis/httpd-php-dev:7.1-ubuntu
-    - fpfis/httpd-php-dev:7.2-ubuntu
+    - fpfis/httpd-php-dev:7.1
+    - fpfis/httpd-php-dev:7.2
   COMPOSER_BOUNDARY:
     - lowest
     - highest