[bug#50080] Commit updating SUNDIALS to 6.1.1.

[Paul A. Patience]

Hi Ludo,

I see that you have updated SUNDIALS to 6.1.1.
When last I updated it (to 5.7.0) [1], I encountered issues in 32-bit vs 64-bit
indices, which I see no mention of in your commit.
There were also some other issues which I mentioned in my patch series'
commit messages.

Do you know if the update to 6.1.1 renders the issues extraneous?
A good test would be adding SUNDIALS as a propagated input to
deal.II.
That had been my original goal.

Thanks,
Paul

[1]: https://issues.guix.gnu.org/50080