ismutable wrong for FillArrays

FillArrays are not mutable.

julia> ArrayInterface.ismutable(typeof(Fill(4, (2,2))))
true

I think that
https://github.com/SciML/ArrayInterface.jl/blob/730592e19c5e3effb086a5cc0b61ecc1a1936a76/src/ArrayInterface.jl#L75-L81

Should be

 function ismutable(::Type{T}) where {T<:AbstractArray} 
     if parent_type(T) <: T 
         return false  # no parent, and have not hit a type we know about 
     else 
         return ismutable(parent_type(T)) 
     end 
 end

ismutable{::Type{<:Array}} = true
ismutable{::Type{<:SparseVector}} = true
ismutable{::Type{<:SparseMatrixCSC}} = true
ismutable{::Type{<:BitArray}} = true

Alternatively
the fallback case could be: return T.mutable rather than false.
On the assumption that if you are a mutable struct that has subtypes AbstractArray you probably have defined setindex

Read src/ArrayInterface.jl lines 75-81 and reproduce the FillArrays example showing ArrayInterface.ismutable(typeof(Fill(4, (2,2)))) returning true. Compare the proposed parent-type recursion and T.mutable fallback, then verify that FillArrays are classified as immutable while the listed mutable array types remain true.