ci: Use openSUSE image for code style checking

CentOS does not have the cppi package, so some code style checks are
skipped. Switch to a openSUSE image to do the code style checks.
Signed-off-by: NJonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>

.gitlab-ci.yml

@@ -491,7 +491,7 @@ website:
 
 codestyle:
   stage: builds
-  image: $CI_REGISTRY_IMAGE/ci-centos-8:latest
+  image: $CI_REGISTRY_IMAGE/ci-opensuse-151:latest
   before_script:
     - *script_variables
   script: