Release process: drop obsolete step

We don't have "Debian packages ones" anymore, and the previous steps
already ensure we have pushed stable, devel, and master to tails.git.

wiki/src/contribute/release_process.mdwn

@@ -1831,8 +1831,6 @@ If you just released a final release
 1. Push the resulting branches.
 1. Make sure Jenkins manages to build all updated major branches:
    <https://jenkins.tails.boum.org/>.
-1. Make sure you pushed all changes in every of our Git repo (including our
-   Debian packages ones).
 1. In [[contribute/calendar]], remove the entries about the version that you've
    just released.
 1. Check the Mozilla release calendars: