ci/gha: add build with minimum dependency versions
ci/gha: add build with minimum dependency versions

The container is purpose built to have the minimum version of all direct
dependencies as well as an old'ish compiler and autotools toolchain.

astiob/libass,ShiftMediaProject/libass,libass/libass,libass/libass,MrSmile/libass,MrSmile/libass,ShiftMediaProject/libass,astiob/libass