[buildbot] ci: docker: deploy automatically only on default branch and tags

[LEDE Commits]

ynezz pushed a commit to buildbot.git, branch master:
https://git.openwrt.org/46c1b080d3eadebbb504150788ddd2d9424eb28f

commit 46c1b080d3eadebbb504150788ddd2d9424eb28f
Author: Petr Štetiar <ynezz at true.cz>
AuthorDate: Wed Nov 3 14:59:26 2021 +0100

    ci: docker: deploy automatically only on default branch and tags
    
    In commit fecd899e8189 ("docker: deploy only manually and on
    master/tags") we've introduced manual deployment of the Docker images,
    but this is unneeded additional manual step, so rather prefer automatic
    deployment. While at it, convert to usage of `rules:` as `only:` is
    deprecated and `rules:` are preferred.
    
    Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 .gitlab/docker.yml | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/.gitlab/docker.yml b/.gitlab/docker.yml
index 9140432..5cc4951 100644
--- a/.gitlab/docker.yml
+++ b/.gitlab/docker.yml
@@ -23,10 +23,9 @@
 
 .deploy Docker image:
   extends: .docker in docker
-  only:
-    - master
-    - tags
-  when: manual
+  rules:
+    - if: $CI_COMMIT_TAG
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
   script:
     - export IMAGE_NAME="$(echo $CI_JOB_NAME | sed 's/deploy Docker image \(.*\)/\1/')"
     - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY