fix homebrew install link in setup script (#686)

Author: xx01cyx

build_support/packages.sh

@@ -69,7 +69,7 @@ install_mac() {
   # Install Homebrew.
   if test ! $(which brew); then
     echo "Installing Homebrew (https://brew.sh/)"
-    ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
+    bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
   fi
   # Update Homebrew.
   brew update