When using GitHub Action, debug is always set

[mattsb42-aws]

Because of the way that the debug (verbosity) value is passed through GitHub Actions and Docker, it looks like not-grep is always getting some value set, which is interpreted as enabling increased verbosity.

https://github.com/mattsb42-aws/aws-encryption-sdk-javascript/runs/686814382?check_suite_focus=true

I think the right answer here might be to change to require a specific value in the debug environment variable rather than just requiring any value.