Update main.yml

Author: mcbarton

.github/workflows/main.yml

@@ -331,6 +331,7 @@ jobs:
                          --contents notebooks/audio/audio.wav &
           if [[ "${os}" == "macos"* ]]; then
             brew install coreutils
+            export PATH="$HOMEBREW_PREFIX/opt/coreutils/libexec/gnubin:$PATH"
           fi 
           python -m pip install nbdime
           python -m pip install selenium