fix ruby 2.5 docker image
fix ruby 2.5 docker image

force the installation of ruby2.5-rubygem-gem2rpm. Otherwise we get
ruby2.1-rubygem-gem2rpm and that pulls in ruby2.1

Signed-off-by: Jordi Massaguer Pla <6858cec916b2a25e416959701ca32d40d47aefc7@suse.de>

openSUSE/docker-containers