Internals of BigFloat getting changed in 1.12

[KristofferC]

See JuliaLang/julia#55906.

Now causes

libfasttransforms: Error During Test at /home/pkgeval/.julia/packages/FastTransforms/vOKsU/test/libfasttransformstests.jl:5
  Got exception outside of a @test
  not compatible with mpfr
  Stacktrace:
    [1] error(s::String)
      @ Base ./error.jl:44
    [2] unsafe_convert(::Type{Ref{BigFloat}}, x::Base.RefValue{BigFloat})
      @ Base.MPFR ./mpfr.jl:212
    [3] plan_ultra2ultra(::Type{BigFloat}, n::Int64, λ::Float64, μ::Float64; norm1::Bool, norm2::Bool)
      @ FastTransforms ~/.julia/packages/FastTransforms/vOKsU/src/libfasttransforms.jl:646
    [4] plan_ultra2ultra(::Type{BigFloat}, n::Int64, λ::Float64, μ::Float64)
      @ FastTransforms ~/.julia/packages/FastTransforms/vOKsU/src/libfasttransforms.jl:645
    [5] plan_ultra2ultra(::Matrix{BigFloat}, ::Float64, ::Vararg{Float64}; z::@Kwargs{})
      @ FastTransforms ~/.julia/packages/FastTransforms/vOKsU/src/libfasttransforms.jl:434
    [6] plan_ultra2ultra(::Matrix{BigFloat}, ::Float64, ::Float64)
      @ FastTransforms ~/.julia/packages/FastTransforms/vOKsU/src/libfasttransforms.jl:434
    [7] top-level scope
      @ ~/.julia/packages/FastTransforms/vOKsU/test/libfasttransformstests.jl:6
    [8] macro expansion
      @ /opt/julia/share/julia/stdlib/v1.12/Test/src/Test.jl:1771 [inlined]

[stevengj]

Should be fixed by JuliaLang/julia#57367