Xpad 5.7 released

Written for Xpad by Arthur Borsboom on 2022-03-15

Another maintenance release.

- Bug fix: systray [Show all] / [Hide all]
- Dependency: pango v1.50 > v1.32
- Dependency: replaced libappindicator > libayatana-appindicator, since libappindicator is unmaintained