Fix release job when build is in progress

+ git push origin 2021
To https://github.com/nuxeo/nuxeo-lts
 ! [rejected]                2021 -> 2021 (fetch first)
error: failed to push some refs to 'https://github.com/nuxeo/nuxeo-lts'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
script returned exit code 1