Fix documentation build cache corruption

[ChrisRackauckas]

[ChrisRackauckas]

@avik-pal or @oxinabox, would anyone happen to know why ChainRulesCore is giving world age issues?

https://buildkite.com/julialang/scimldocs/builds/4206#018ec037-416d-4dee-a985-0fa5135a0aa1/720-2219

│    MethodError: no method matching ChainRulesCore.ZeroTangent()
│    The applicable method may be too new: running in world age 61534, while current world is 189034.

[oxinabox]

I have never seen anything like that. ZeroTangent() does nothing fancy with eval or @generated or anything

[ChrisRackauckas]

CC @maleadt, this also is weird stuff at exactly the same places that said "Not Implemented". Something seems very odd.

[gbaraldi]

Are we able to get this under rr?

[ChrisRackauckas]

Solved by... removing DiffEqFlux from the docs build. https://github.com/SciML/SciMLDocs/pull/232. Not an ideal situation and quite scary to know this exists, but it gets the docs building