add the .P-3 file extension

[mancebius]

Good morning

Thanks for this extension , it's very useful. Could you add the .P-3 file extension? In my work we use that and it would be very useful

Thank you

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity.

[mikecentola]

Sure Can! I'll add it to the work for v0.8. Sorry for taking so long to get back to this project. I've been dealing with some life issues.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity.