Run checks on v21.12 (MR 7)

.ci/generate_page.sh

@@ -3,6 +3,7 @@
 export BRANCHES="
 	master
 	v21.06
+	v21.12
 	"
 
 mkdir -p public

.gitlab-ci.yml

@@ -55,6 +55,17 @@ upstream-compat-v21.06:
     paths:
       - "*.check-passed"
 
+upstream-compat-v21.12:
+  stage: check
+  <<: *only-default
+  allow_failure: true
+  script:
+  - ./test_upstream_compat_setup.sh "v21.12"
+  artifacts:
+    when: always
+    paths:
+      - "*.check-passed"
+
 pages:
   stage: badge
   <<: *only-default