Add gpsampler

[michaelriedl]

Motivation

I wanted to bring the Optuna plugin up to date with the newest version. I made the necessary changes to make the plugin compatible. I also added in the GPSampler even though it is still experimental since some people may want to use it.

Have you read the Contributing Guidelines on pull requests?

Yes.

Test Plan

I modified the existing tests in the plugin folder. I have tested that they pass on my WSL setup.

Related Issues and PRs

Issues:
#2562
#2162

PRs:
#2360

[michaelriedl]

I did not realize that I basically duplicated #2360. Can we merge one of these in?

[michaelriedl]

It also appears that the workflows for CI do not trigger with a PR from a forked branch.

[himkt]

Hello @jesszzzz, can we ask you to review the PR?

[himkt]

Let me kindly ping @jesszzzz.

[jesszzzz]

Sorry for the delay! I do expect some tests will break from this, #3020 enables running CI on forked PRs so please rebase when that's merged. Otherwise these changes look fine to me!

[himkt]

Thank you for letting us know!
cc. @michaelriedl

[michaelriedl]

Sorry for the delay! I do expect some tests will break from this, #3020 enables running CI on forked PRs so please rebase when that's merged. Otherwise these changes look fine to me!

@jesszzzz Rebased as requested.

[michaelriedl]

@jesszzzz it looks like you need to approve the 2 workflows to run since I am a first time contributor. I ran all the Pytest tests locally without issue, just need to run the workflows.

[himkt]

Let me kindly ping as well. 🙏 @jesszzzz

[tadejsv]

@jesszzzz any updates here?

[nefario7]

Any updates on getting this merged? Getting this in will be awesome
@jesszzzz

[omry]

Thank you for the PR and for pushing the Optuna plugin forward.

I am going to close this as superseded by #3046, which is the current Optuna compatibility upgrade PR. The Optuna API compatibility work is still relevant, but I would like to handle it in that newer compatibility-focused PR/lane rather than keep multiple overlapping upgrade PRs open.

The GPSampler addition is also a separate enhancement from the compatibility upgrade, especially because it brings heavier optional dependencies. That should be considered separately after the core Optuna compatibility work is settled.