The source project of this merge request has been removed.
Create a CI builder container to cache dependency resolution
This speeds up CI builds considerably since it avoids using a time consuming before_script in the CI manifest.
Note that this branch does fail to build since I do not have access privileges to push a container image into Poppler's upstream container registry at registry.freedesktop.org/poppler/poppler/builder:v1.
Closes adamreichold/poppler#1