databases/py-harlequin: Update to 2.8.0

ChangeLog:

• https://github.com/tconbeer/harlequin/releases/tag/v2.6.0
• https://github.com/tconbeer/harlequin/releases/tag/v2.7.0
• https://github.com/tconbeer/harlequin/releases/tag/v2.8.0

Reported by: Ted Conbeer <notifications@github.com>