Queue waiting publishes instead of cancelling all but one

The publish job runs in the concurrency group "publish" with
cancel-in-progress: false. By default such a group holds one running job
and one waiting job: when a third arrives, GitHub cancels the one that was
waiting and puts the new one in its place. That merge's publish is dropped,
with no publish record, PR comment or log line, and nothing reruns it.

17 of the last 181 publish runs ended cancelled, 12 of them from one burst
of merges on 2026-09-28. openvino-genai 2026.4.0.0-1 (#620) was one of
those and is still in no channel.

queue: max lets up to 100 jobs wait in the group and run in the order they
reach it. Nothing else changes: one publish at a time, and a running one is
not interrupted. unpublish.yml shares the group, so it gets the same
setting.

actionlint 1.7.12, the latest release, predates the key and reports it as
unexpected in both files (rhysd/actionlint#654). It reports nothing else.

.github/workflows/unpublish.yml

@@ -25,9 +25,11 @@ jobs:
     environment: publish
     timeout-minutes: 15
     # The publish job's group: one writer per channel database at a time.
+    # queue: max, as there: a waiting job is queued, not replaced.
     concurrency:
       group: publish
       cancel-in-progress: false
+      queue: max
     steps:
       - uses: actions/checkout@v4
         with: