Invalid app.json: config var "SFDX_DEV_HUB_AUTH_URL" is required

[shariatululoom]

Hello Wade

while creating Review App, we are getting Invalid app.json: config var "SFDX_DEV_HUB_AUTH_URL" is required in the logs.
setup.sh created our all apps in heroku but stuck over the "jq command not found error".

Please have an insight to it. Thanks