package/xmrig: bump version to 6.21.3
Changelog: https://github.com/xmrig/xmrig/blob/master/CHANGELOG.md
Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit cd83b50bdca87c74dfd4a4860de52eb645b76394)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>