CI sage: remove unneeded ubuntu packages, install fflas-ffpack for linbox configure (#336)
CI sage: remove unneeded ubuntu packages, install fflas-ffpack for linbox configure (#336)

* .github/workflows/ci-sage.yml (dist): Do not install ubuntu packages libgivaro-dev, fflas-ffpack

* .github/workflows/ci-sage.yml (dist): Install fflas-ffpack before configuring linbox
linbox-team/fflas-ffpack,linbox-team/fflas-ffpack,linbox-team/fflas-ffpack