Handle error when tput is called under Docker

What does this Merge Request do and why?

This MR fixes an issue where attempting to display the git diff output when a config file is about to be updated causes an error. The error occurs when tput colors is called which when run headless via Docker results in an error, which is now handled.

Merge Request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise Issue to follow-up.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.

Closes #1346 (closed)