Merge branch 'feature/opensuse151' into 'master'

Drop openSUSE v15.1

See merge request !9

.gitlab-ci.yml

@@ -81,20 +81,3 @@ upload/openSUSE/15.2:
   <<: *upload
   dependencies:
     - build/opensuse/15.2
-
-build/opensuse/15.1:
-  <<: *build
-  variables:
-    DOCKER_IMAGE: opensuse/15.1
-
-test/opensuse/15.1:
-  <<: *test
-  variables:
-    DOCKER_IMAGE: opensuse/15.1
-  dependencies:
-    - build/opensuse/15.1
-
-upload/openSUSE/15.1:
-  <<: *upload
-  dependencies:
-    - build/opensuse/15.1