Fix the failing CI build

Author: christiangnrd

test/utils.jl

@@ -1,7 +1,7 @@
 using Flux
 using Flux: throttle, nfan, glorot_uniform, glorot_normal,
              kaiming_normal, kaiming_uniform, orthogonal, truncated_normal,
-             sparse_init, identity_init, stack, unstack, batch, unbatch,
+             sparse_init, identity_init, unstack, batch, unbatch,
              unsqueeze, params, loadparams!, loadmodel!
 using StatsBase: var, std
 using Statistics, LinearAlgebra
@@ -326,14 +326,14 @@ end
 
 @testset "Stacking" begin
   x = randn(3,3)
-  stacked = stack([x, x], dims=2)
+  stacked = Flux.MLUtils.stack([x, x], dims=2)
   @test size(stacked) == (3,2,3)
 
   stacked_array=[ 8 9 3 5; 9 6 6 9; 9 1 7 2; 7 4 10 6 ]
   unstacked_array=[[8, 9, 9, 7], [9, 6, 1, 4], [3, 6, 7, 10], [5, 9, 2, 6]]
   @test unstack(stacked_array, dims=2) == unstacked_array
-  @test stack(unstacked_array, dims=2) == stacked_array
-  @test stack(unstack(stacked_array, dims=1), dims=1) == stacked_array
+  @test Flux.MLUtils.stack(unstacked_array, dims=2) == stacked_array
+  @test Flux.MLUtils.stack(unstack(stacked_array, dims=1), dims=1) == stacked_array
 end
 
 @testset "Batching" begin