Making sure channel flag is set correctly

Author: atalman

.github/workflows/build-m1-binaries.yml

@@ -141,8 +141,8 @@ jobs:
           if [[ $CHANNEL == "test" ]]; then
             setup_cuda
             setup_base_build_version
-            export CONDA_CHANNEL_FLAGS="pytorch-test"
             setup_macos
+            export CONDA_CHANNEL_FLAGS="-c pytorch-test"
           else
             setup_cuda
             setup_build_version