tests: suppress push in test-service-dulwich.t for recent releases
Pushing to Dulwich itself is broken in recent releases; I've posted a PR that should fix that, so we assume the next release will fix it.
This instance will be upgraded to Heptapod 18.5.1 on 2025-11-13 between 17:00 and 18:00 UTC+2
Pushing to Dulwich itself is broken in recent releases; I've posted a PR that should fix that, so we assume the next release will fix it.