Error When attempting to deploy to Heroku `django.core.exceptions.ImproperlyConfigured: Missing environment variable: SFDX_CLIENT_CALLBACK_URL`

[camerongoodman]

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Error on initial push to Heroku after running git push heroku main django.core.exceptions.ImproperlyConfigured: Missing environment variable: SFDX_CLIENT_CALLBACK_URL

Line 179 in the setup documentation heroku-setup.md says to use SF_CALLBACK_URL however looks like it needs SFDX_CLIENT_CALLBACK_URL instead.