Skip the exponent function

It is a Base function that returns a scalar.

https://github.com/SciML/DiffEqBase.jl/blame/master/src/internal_itp.jl#L46

https://github.com/SciML/OrdinaryDiffEq.jl/actions/runs/14272335727/job/40008186966?pr=2662#step:6:1251

@oscardssmith

Author: ChrisRackauckas

src/ReverseDiff.jl

@@ -26,7 +26,7 @@ using ChainRulesCore
 const ARRAY_TYPES = (:AbstractArray, :AbstractVector, :AbstractMatrix, :Array, :Vector, :Matrix)
 const REAL_TYPES = (:Bool, :Integer, :AbstractIrrational, :Rational, :BigFloat, :BigInt, :AbstractFloat, :Real, :Dual)
 
-const SKIPPED_UNARY_SCALAR_FUNCS  = Symbol[:isinf, :isnan, :isfinite, :iseven, :isodd, :isreal, :isinteger]
+const SKIPPED_UNARY_SCALAR_FUNCS  = Symbol[:isinf, :isnan, :isfinite, :iseven, :isodd, :isreal, :isinteger, :exponent]
 const SKIPPED_BINARY_SCALAR_FUNCS = Symbol[:isequal, :isless, :<, :>, :(==), :(!=), :(<=), :(>=)]
 
 # Some functions with derivatives in DiffRules are not supported