fix: TravisCI failures & status

[mayeut]

fix issues with Travis CI seen while working on #1961

[mayeut]

Shall we add an allowed failure for s390x (at least for now) ?
IBM builds are broken at the moment in Travis CI, I sent a mail to the support on Aug 2, 2024. The latest update after asking for an update was today:

Hey Matthieu,

Thanks for your continued patience, and we appreciate your understanding.

Our team is actively looking into the reported issue and is working hard to find a solution. We will keep you posted on the progress.

Thanks again for your patience and cooperation.

Best,

[henryiii]

Seems fine to allow failure for now.

[joerick]

agreed, lets allow failure on that.