keystone 21.0.0.0rc1 release candidate

meta:version: 21.0.0.0rc1
meta:diff-start: -
meta:series: yoga
meta:release-type: release candidate
meta:pypi: no
meta:first: no
meta:release:Author: Elod Illes <elod.illes@est.tech>
meta:release:Commit: Elod Illes <elod.illes@est.tech>
meta:release:Change-Id: Ib4d73eb16838e24cd4c3b867e02ae62b613b73b7
meta:release:Code-Review+2: Hervé Beraud <herveberaud.pro@gmail.com>
meta:release:Code-Review+2: Elod Illes <elod.illes@est.tech>
meta:release:Workflow+1: Elod Illes <elod.illes@est.tech>