CI: dev kernel allow failure

The dev kernel can frequently fail, and is not anything that is used in
production.  Allow failure to prevent CI issues but still notify that
there are potential issues.

Signed-off-by: Jon Mason <jon.mason@arm.com>

.gitlab-ci.yml

@@ -43,9 +43,21 @@ stages:
   extends: .setup
   variables:
     KUBERNETES_CPU_REQUEST: $CPU_REQUEST
-  only:
-    variables:
-      - $BUILD_ENABLE_REGEX == null || $CI_JOB_NAME =~ $BUILD_ENABLE_REGEX
+  rules:
+    # Don't run MR pipelines
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+      when: never
+    # Don't run pipelines for tags
+    - if: $CI_COMMIT_TAG
+      when: never
+    # Don't run if BUILD_ENABLE_REGEX is set, but the job doesn't match the regex
+    - if: '$BUILD_ENABLE_REGEX != null && $CI_JOB_NAME !~ $BUILD_ENABLE_REGEX'
+      when: never
+    # Allow the dev kernels to fail and not fail the overall build
+    - if: '$KERNEL == "linux-yocto-dev"'
+      allow_failure: true
+    # Catch all for everything else
+    - if: '$KERNEL != "linux-yocto-dev"'
   script:
     - KASFILES=$(./ci/jobs-to-kas "$CI_JOB_NAME")
     - kas shell --update --force-checkout $KASFILES -c 'cat conf/*.conf'