CI: drop installation on rolling

Change-Id: I7bb9a066043c308f41df17fa388c0bdc1066de26
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0d5a223..4ff86d1 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -15,11 +15,3 @@
     - R -q -e 'library(RKorAPClient); testthat::test_dir("tests/testthat")'
     - end_section testing
 
-build-rkorapclient-on-rolling:
-  extends: .install-rkorapclient
-  image: ubuntu:rolling
-  script:
-    - start_section testing "Testing RKorAPClient"
-    - R -q -e 'library(RKorAPClient); testthat::test_dir("tests/testthat")'
-    - end_section testing
-