fix variable name

.gitlab-ci.yml

@@ -1,5 +1,5 @@
 before_script:
-  - export CI_CURNN_TEST=true
+  - export CI_DISABLE_CURNN_TEST=true
 
 variables:
   CI_IMAGE_TAG: 'cuda'

test/cuda/cuda.jl

@@ -41,7 +41,7 @@ end
 if CuArrays.libcudnn != nothing
     @info "Testing Flux/CUDNN"
     include("cudnn.jl")
-    if !haskey(ENV, "CI_CURNN_TEST")
+    if !haskey(ENV, "CI_DISABLE_CURNN_TEST")
       include("curnn.jl")
     end
 end