payum/server missing DOM extension

[evilfrog]

Current payum/server:latest image (image id 3ab4418f87bc) has no XML/DOM extension installed.

There's php7.1-xml installed, but the default version uses php7.2 and therefore looks for extensions in different directory.

/etc/php/7.1/mods-available/ vs /etc/php/7.2/mods-available/

I see there's Ondrej's repo added to apt's source lists, so the quick fix is just:

FROM payum/server

RUN apt-get update && \
    apt-get install -y php7.2-xml

[evilfrog]

Same thing for soap and probably some other extensions...