Merge branch 'feature/sles-12-4' into 'master'

Drop SLES 12.4

See merge request packaging/rpm-icinga2!13

.gitlab-ci.yml

@@ -245,23 +245,6 @@ upload/SUSE/12.5:
   dependencies:
     - build/sles/12.5
 
-build/sles/12.4:
-  <<: *build
-  variables:
-    DOCKER_IMAGE: sles/12.4
-
-test/sles/12.4:
-  <<: *test
-  variables:
-    DOCKER_IMAGE: sles/12.4
-  dependencies:
-    - build/sles/12.4
-
-upload/SUSE/12.4:
-  <<: *upload
-  dependencies:
-    - build/sles/12.4
-
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 # openSUSE
 ###################################