PMM-7 add notification (#1510)
PMM-7 add notification (#1510)

* PMM-7 add notification

* Update pmm/pmm2-prepare-release-candidate.groovy

Co-authored-by: Alex Tymchuk <ca2ef7b7b2fa0df38af37caba9edccf94c142988@percona.com>

Co-authored-by: Alex Tymchuk <ca2ef7b7b2fa0df38af37caba9edccf94c142988@percona.com>
Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines