git: Sync between GitLab, Gerrit, and GitHub.

It was previously only GitLab and GitHub.

Change-Id: I2aa3041c030f4aea7384947e586fe433d80e2742
diff --git a/git/git.yaml b/git/git.yaml
index 3af8f44..726f8e1 100644
--- a/git/git.yaml
+++ b/git/git.yaml
@@ -292,8 +292,13 @@
                       fi
 
                       cd "/git/repositories/mulk/$x.git"
-                      git fetch "https://gitlab.benkard.de/mulk/${x}.git" master:master
-                      git push "git@github.com:benkard/${x}.git" master
+
+                      for branch in master main
+                      do
+                          git fetch "https://gitlab.benkard.de/mulk/${x}.git" "$branch:$branch" && \
+                          ( git push "ssh://mulk@gerrit.benkard.de:29418/${x}.git" "$branch"; \
+                            git push "git@github.com:benkard/${x}.git" "$branch" )
+                      done
                   done
                   true
               env: