[Tails-l10n] Release schedule for Tails 6.7

Hi,

boyska will be the RM for Tails 6.7

The current plan is:
- Monday, September 9: build images, start testing
- Tuesday, September 10: releasing

@testers, please let the RM know how much time you'll have for manual QA
from Monday 15:00 to Tuesday 11:00 (Europe/Berlin)

@developers, please don't push any change to the branch used for the release
on these days.

--
intrigeri