Investigate nightly CI build issues

[ToucheSir]

e.g. latest commit of this writing: https://github.com/FluxML/Flux.jl/runs/3708588387

We're currently failing on JuliaArrays/ArrayInterface.jl#205, which should've been fixed in [email protected]. Flux has a compat bound on 3.1 and I was able to add the new version locally without any conflicts, so do we just need to bump the Manifest?

[CarloLucibello]

Our Manifest is 2 months old, we should get rid of it or automatize the update, the current situation really doesn't make sense.

[CarloLucibello]

let's see if CI in #1725 goes all green

[DhairyaLGandhi]

We have updated it in #1708 and can automate updating it too.

[ToucheSir]

Seems like we're back to BoundsError(a=Array{Core.Compiler.VarState, (3,)}[Core.Compiler.VarState(typ=Core.Const(val=ZygoteRules._pullback), undef=false), Core.Compiler.VarState(typ=Zygote.Context, undef=false), Core.Compiler.VarState(typ=Core.Const(val=Main.var"#13"), undef=false)], i=(4,)). Did anyone ever figure out what that was about?

[ToucheSir]

Zygote is good as of FluxML/Zygote.jl#1125, I guess we'll see what's left once a new patch release is cut.