Use of set-env has been disabled in Github Actions

[quinceleaf]

[Just a note: I'm working through using the tutorial/adapting it for my own project and have run into the following issue. As I work through the issue and make the necessary changes for my own project, I'll update this issue with suggested fix(es).]

The use of set-env in Github Actions has been disabled (see GitHub Actions: Deprecating set-env and add-path commands)

Running as currently available in /.github/workflows/main.yml throws

Error: The `set-env` command is disabled. Please upgrade to 
using Environment Files  or opt into unsecure command execution 
by setting the `ACTIONS_ALLOW_UNSECURE_COMMANDS` 
environment variable to `true`. 

[mjhea0]

Updated