Refactor Debian support

What does this MR do?

Remove code branch for deb support. This is no longer needed in v3 since DebVersion is a Comparable.

Monkey patch DebVersion#to_s to fix it.

What are the relevant issue numbers?

None

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for this project, if necessary
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Security reports checked/validated by reviewer