fix MacOS cmake workflow (#4203)

* fix MacOS cmake workflow

* try only mkl

* only pin mkl on MacOs

* fix
Co-authored-by: Francisco Massa <fvsmassa@gmail.com>

packaging/build_cmake.sh

@@ -28,7 +28,15 @@ fi
 setup_visual_studio_constraint
 setup_junit_results_folder
 
-conda install -yq pytorch=$PYTORCH_VERSION $CONDA_CUDATOOLKIT_CONSTRAINT $CONDA_CPUONLY_FEATURE  -c "pytorch-${UPLOAD_CHANNEL}"
+if [[ "$(uname)" == Darwin ]]; then
+  # TODO: this can be removed as soon as mkl's CMake support works with clang
+  #  see https://github.com/pytorch/vision/pull/4203 for details
+  MKL_CONSTRAINT='mkl==2021.2.0'
+else
+  MKL_CONSTRAINT=''
+fi
+
+conda install -yq \pytorch=$PYTORCH_VERSION $CONDA_CUDATOOLKIT_CONSTRAINT $CONDA_CPUONLY_FEATURE $MKL_CONSTRAINT -c "pytorch-${UPLOAD_CHANNEL}"
 TORCH_PATH=$(dirname $(python -c "import torch; print(torch.__file__)"))
 
 if [[ "$(uname)" == Darwin || "$OSTYPE" == "msys" ]]; then