Automate scheduled publications

[rth]

For making post announcements easier, it would be good to have an automated system for publishing at a given date/time.

It could be either,

• schedule merging of PR: I looked at https://github.com/marketplace/actions/merge-schedule unfortunately it doesn't work for forks for security reasons
• mering with a date in the future (in which case the post would be ignored) then re-triggering build at the expected publication time.

[rth]

Installed https://github.com/marketplace/pr-scheduler on this repo which should do the job.

[ryanking13]

Thanks Roman!