Removed a dispatch on review function.jl

Removed the dispatch as per the review comment.

Author: ParasPuneetSingh

src/function.jl

@@ -76,19 +76,6 @@ function instantiate_function(f::MultiObjectiveOptimizationFunction, x, ::SciMLB
         observed = f.observed)
 end
 
-function instantiate_function(f::MultiObjectiveOptimizationFunction, x, adtype::ADTypes.AbstractADType,
-        p, num_cons = 0)
-    adtypestr = string(adtype)
-    _strtind = findfirst('.', adtypestr)
-    strtind = isnothing(_strtind) ? 5 : _strtind + 5
-    open_nrmlbrkt_ind = findfirst('(', adtypestr)
-    open_squigllybrkt_ind = findfirst('{', adtypestr)
-    open_brkt_ind = isnothing(open_squigllybrkt_ind) ? open_nrmlbrkt_ind :
-                    min(open_nrmlbrkt_ind, open_squigllybrkt_ind)
-    adpkg = adtypestr[strtind:(open_brkt_ind - 1)]
-    throw(ArgumentError("The passed automatic differentiation backend choice is not available. Please load the corresponding AD package $adpkg."))
-end
-
 function instantiate_function(f::MultiObjectiveOptimizationFunction, cache::ReInitCache, ::SciMLBase.NoAD,
         num_cons = 0)
     jac = f.jac === nothing ? nothing : (J, x, args...) -> f.jac(J, x, cache.p, args...)