[doc] Minor update to macos update-ci script ran every week [ci skip]

doc/macos-ci-install/update-ci.sh

@@ -5,9 +5,10 @@ echo "Updating homebrew..."
 brew=/usr/local/bin/brew
 ${brew} update
 ${brew} upgrade
+echo "Updating homebrew casks..."
+${brew} cask upgrade
 ${brew} cleanup
 
-
 # Updates PIP packages installed
 function pipupdate() {
   echo "Updating ${1} packages..."