API Deprecate average=0 in SGD

[jeremiedbb]

Fixes #28389

Makes it consistent with the rest of the code base where we require true boolean for boolean parameters.

Based on the param description: "If set to an int greater than 1, averaging will begin once the total number of samples seen reaches average". When not paying enough attention, one might consider that average=0 means start averaging right away, but it's only valid for strictly positive integers. Deprecating average=0 prevents the confusion once and for all.

[github-actions]

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[lesteve]

Maybe mention that average=False should be used (rather than average=0) in the changelog.

Other than this LGTM

[lesteve]

BTW I think you don't need [doc quick] in the commit message, since the "quick build" (i.e. make html-noplot) is the default behaviour if there is no change to examples.

[jeremiedbb]

Maybe mention that average=False should be used (rather than average=0) in the changelog.

it's already there :)

[glemaitre]

LGTM. We can merge if the doc CI does not complain.