update heroku cli installation script (#8566)

Author: sergei-pyshnoi

images/linux/scripts/installers/heroku.sh

@@ -1,10 +1,21 @@
 #!/bin/bash -e
 ################################################################################
 ##  File:  heroku.sh
-##  Desc:  Installs Heroku CLI
+##  Desc:  This script installs Heroku CLI. Based on instructions found here: https://devcenter.heroku.com/articles/heroku-cli
 ################################################################################
 
-# Install Heroku CLI
-curl -fsSL https://cli-assets.heroku.com/install.sh | sh
+## Install Heroku CLI
 
-invoke_tests "Tools" "Heroku"
+# add heroku repository to apt
+echo "deb https://cli-assets.heroku.com/channels/stable/apt ./" > /etc/apt/sources.list.d/heroku.list
+
+# install heroku's release key for package verification
+curl https://cli-assets.heroku.com/channels/stable/apt/release.key | apt-key add -
+
+# install heroku
+apt-get update -y && apt-get install -y heroku
+
+# remove heroku's apt repository
+rm /etc/apt/sources.list.d/heroku.list
+
+invoke_tests "Tools" "Heroku"