Update test setup for GitHub Actions

- Do the (hopefully now) correct test to check we are on macOS.
- Fix brew command-line syntax for installing google-chrome.

tests/scripts/setup_osx_env.sh

@@ -1,8 +1,8 @@
 #!/bin/bash
   
-if [ "${TRAVIS_OS_NAME}" == "osx" ]
+if [ "${RUNNER_OS}" == "macOS" ]
   then
-    brew cask install google-chrome 
+    brew install google-chrome 
     sudo Xvfb :99 -ac -screen 0 1024x768x8 &
     export CHROME_BIN="/Applications/Google Chrome.app"
     npm run test:prepare > /dev/null &