The better long-term solution might be to drop support for Julia < 1.9 or make ADTypes a proper dependency on Julia < 1.9 (problems with AD backends might still pop up), but the PR is just intended as a quick hotfix.
I think we should definitely do this, not having proper compat bounds on Julia < 1.9 seems pretty dangerous in particular in the AD ecosystem. IMO we could make the switch right away after this bugfix release.
34 broke ADTypes support on older Julia versions since the Requires-based loading does not respect compat entries: https://github.com/TuringLang/Turing.jl/issues/2305#issuecomment-2288399653
The better long-term solution might be to drop support for Julia < 1.9 or make ADTypes a proper dependency on Julia < 1.9 (problems with AD backends might still pop up), but the PR is just intended as a quick hotfix.