Bump compat constraint on Functors to 0.5

[axsk]

Summary

Proposed changes

• ...

What alternatives have you considered?

Breaking changes

[theogf]

You would need to make sure that the new behaviour of @functor is still correct (it looks like now being a leaf is opt-in rather than opt-out)

[gnadt]

I'll kindly note that KernelFunctions is indirectly limiting other packages (via the Functors dependency) from updating Flux. Our package will unfortunately have to drop KernelFunctions instead. I'm not familiar with the internals or testing of the KernelFunctions package, but the CI results on 1.6 and 1 for this PR looks to be the same as the previous PR.

[theogf]

I will take a closer look.

[theogf]

It looks like the tests are failing like on master, however inspecting the resolution it looks like 0.4.12 was used in the tests. @axsk could you also update the compat in test/Project.toml?

[sathvikbhagavan]

A gentle bump on this. Its blocking upgrading Flux in Surrogates.jl