Update heroku multibuildpack on all your apps
#!/bin/bash
request=$(heroku apps --json)
apps=$(echo $request | jq -r '.[] | select(.buildpack_provided_description=="Multipack").name')
for i in $apps;
do
echo $i
heroku buildpacks:set https://github.com/heroku/heroku-buildpack-multi.git --app $i
done