Bump minimum Armadillo version to 10.8

[conradsnicta]

Bump minimum Armadillo version to 10.8.2.

This allows using the numerous Armadillo API additions and enhancements since 9.800. It also allows assuming throughout the ensmallen codebase that matrices are initialised to zero by default.

Current state of Armadillo versions in various distros:

• Ubuntu 22.04 LTS has Armadillo 10.8.2
• Ubuntu 24.04 LTS has Armadillo 12.6.7
• Debian 12 has Armadillo 11.4.2
• Debian 13 (testing) has Armadillo 12.8.2
• RHEL EPEL 8 & 9 has Armadillo 12.6.6 (subject to future upgrades)

Related: mlpack/mlpack#3760

[zoq]

Looks like the docker images to build uses an older version, will update it tomorrow.

[conradsnicta]

@zoq Sounds good.

[shrit]

Looks good to me, I will approve it after the CI has passed

[rcurtin]

Thanks for all the ifdef cleanups---I didn't realize there was so much of that going on in ensmallen. I'll approve too once we get CI passing and then we can get this merged and a new release out. 👍

[conradsnicta]

@shrit @rcurtin @zoq I've updated the CI config via commits 32015ae and 51c9506
Let me know if this isn't the right way or something else needs to be done

[zoq]

Perfect, I just need to rebuild the docker image that we use on the jenkins server, and that should fix the ensmallen sanity checks job as well.

[conradsnicta]

@zoq Do you mean updating the Ubuntu image? I think the current image uses the old Ubuntu 20.04 release which only has armadillo 9.800.4

[zoq]

@zoq Do you mean updating the Ubuntu image? I think the current image uses the old Ubuntu 20.04 release which only has armadillo 9.800.4

Right, updated the image.

[zoq]

@mlpack-jenkins test this please

[zoq]

@mlpack-jenkins test this please

[zoq]

@mlpack-jenkins test this please

[conradsnicta]

@rcurtin @shrit Could you provide the second approval to facilitate merging? The mlpack bot (that automatically provides the second approval after 24 hours) seems to have gone missing in action.

[rcurtin]

@conradsnicta oh, you're right, I need to add the Github actions script to this repo too. (Basically I went to update mlpack-bot because it stopped working, then it turned out everything it was built on was deprecated, and so in the end I rewrote its functionality as a Github action.)