Defining environment variables for a single workflow
To set a custom environment variable for a single workflow, you can define it using the env key in the workflow file. The scope of a custom variable set by this method is limited to the element in which it is defined. You can define variables that are scoped for:
[A] The entire workflow, by using env at the top level of the workflow file.
[E] The contents of a job within a workflow, by using jobs.<job_id>.env.
[F] A specific step within a job, by using jobs.<job_id>.steps[*].env.
Reference:
https://docs.github.com/en/actions/how-tos/write-workflows/choose-what-workflows-do/use- variables