Hi!

Currently, the Deprecated helper emits a WARNING message when a deprecated option is used, which breaks building sites in strict mode.

This is causing an issue with MkDocs Material, where a deprecated option is still useful in some cases (see a full description in squidfunk/mkdocs-material#7146).

On @squidfunk's suggestion, would it be possible to consider emitting an INFO message instead of a WARNING when Deprecated is used, a bit like it was done in #2907?

Thanks!