build: Update tap scripts for Python 3 compat

This replaces tap-driver and tap-gtester with fresh versions from Cockpit.

https://github.com/cockpit-project/cockpit/pull/9500 https://wiki.gnome.org/Initiatives/GnomeGoals/Python3Porting

Also included are the following gnome-keyring commits that are not included in Cockpit:

• gnome-keyring@918ab836
• gnome-keyring@7e75a62e
• gnome-keyring@7120f44c

Basically a copy of gnome-keyring!4 (merged)