Update .gitlab-ci.yml AUR version: add missing libffi package and re-enable build
After the error log, libffi was missing:
Run Build Command(s):/usr/sbin/make -f Makefile cmTC_b4e9c/fast && /usr/sbin/make: error while loading shared libraries: libffi.so.8: cannot open shared object file: No such file or directory
This should at least fix this error.