Zygote tests are (?) not broken anymore (#339)

FluxML/Zygote.jl#1104 was merged and hence (hopefully) Zygote tests are not broken anymore.

Author: devmotion

test/test_util.jl

@@ -43,12 +43,7 @@ function test_model_ad(model, logp_manual)
 
     y, back = Zygote.pullback(logp_model, x)
     @test y ≈ lp
-    # will be fixed by https://github.com/FluxML/Zygote.jl/pull/1104
-    if Threads.nthreads() > 1
-        @test_broken back(1)[1] ≈ grad
-    else
-        @test back(1)[1] ≈ grad
-    end
+    @test back(1)[1] ≈ grad
 end
 
 """