array API support for mean_gamma_deviance

[EmilyXinyi]

Reference Issues/PRs

towards #26024

What does this implement/fix? Explain your changes.

add array API support for mean_gamma_deviance

Any other comments?

mean_gamma_deviance is a special case of mean_tweedie_deviance where power=2 and both y_pred and y_true must be strictly positive. For this reason I have added the test case check_array_api_regression_metric_gamma (because the y_true in check_array_api_regression_metric contains 0 and I didn't want to change a test that is so widely used). I am not sure if this is the best way to approach this, so if there are any suggestions on how to do this better I would love to know. Thanks!!

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[ogrisel]

Thanks for the PR. I launched the CUDA tests here:

• https://github.com/scikit-learn/scikit-learn/actions/runs/9484845915

EDIT: they pass.

Assuming they pass, LGTM. Just a suggestion to simplify the tests below:

[betatim]

LGTM.

I resolved the conflict and enabled auto-merge