Update runtests.jl

Author: ChrisRackauckas

test/runtests.jl

@@ -72,7 +72,7 @@ end
         @time @safetestset "Unwrapping" include("downstream/unwrapping.jl")
         @time @safetestset "Callback BigFloats" include("downstream/bigfloat_events.jl")
         @time @safetestset "DE stats" include("downstream/stats_tests.jl")
-        @time @safetestset "Ensemble AD Tests" include("downstream/ensemble_ad.jl")
+        isempty(VERSION.prerelease) && @time @safetestset "Ensemble AD Tests" include("downstream/ensemble_ad.jl")
         @time @safetestset "Community Callback Tests" include("downstream/community_callback_tests.jl")
         @time @safetestset "AD via ode with complex numbers" include("downstream/complex_number_ad.jl")
         @time @testset "Distributed Ensemble Tests" include("downstream/distributed_ensemble.jl")