Release criteria

[paulidale]

We need some release criteria for major, minor, patch, alpha and beta releases.
Removed from the versioning policy (wrt the web page):
Release criteria

For a major or minor release, the following release criteria apply:

all open GitHub issues and pull requests older than 2 weeks at the time of
release need to be assessed for relevance to the version being released.
Any flagged with the a milestone for the version to be released must
be closed (see below);
clean builds in GitHub Actions for two days and
no open Coverity issues (not flagged as False Positive or Ignore).

Valid reasons for closing an issue/PR with a milestone for the version
include:

we have just now or sometime in the past fixed the issue;
unable to reproduce (following discussion with original reporter
if possible);
working as intended;
deliberate decision not to fix this issue until a later release (this
wouldn't actually close the issue/PR but change the milestone instead) and
not enough information and unable to contact reporter.

Exceptions require a vote by the OTC as per the OTC whatever.

[paulidale]

Incorporate the beta release checklist from #15326

[t-j-h]

See the 3.0 Release Criteria as the input document.

[t-j-h]

Make sure you look at #11 to see if there is anything missing from there once this is done and if nothing then close that issue.