Fix deprecated zuul queue syntax

Zuul deprecated (and now removed) declaring shared queues at a pipeline
level [1]. This patch fixes the syntax to make the gate work for
adjutant.

[1] https://lists.openstack.org/pipermail/openstack-discuss/2022-May/028603.html

Change-Id: I1420f59cc5a315a47f7a4bfe0ac2a9761d06e11d

.zuul.yaml

@@ -11,6 +11,7 @@
 
 
 - project:
+    queue: adjutant
     templates:
       - publish-openstack-docs-pti
       - build-release-notes-jobs-python3
@@ -20,6 +21,5 @@
       jobs:
         - adjutant-black-style-check
     gate:
-      queue: adjutant
       jobs:
-        - adjutant-black-style-check
+        - adjutant-black-style-check