Disable progress bar with non-interactive terminal

Currently diffenator2 is outputting progress bars into GitHub Actions logs, which is rather unhelpful. (I know there's an official GitHub Action, but it doesn't quite fit my use case. Also, this should still be fixed in diffenator2 itself in my opinion.)

Disabling progress bars for non-interactive sessions would be good, and/or maybe a flag to explicitly disable them, even for interactive environments?