fix ci

Former-commit-id: 809428ee74694037f2aeaff347bbc1e4028fe228
Former-commit-id: 0ba4315e08350157cc427598bab6ae129c1afe08
Former-commit-id: 838b77453bfa3c02cd518124d0f887d4b5c1331d

.gitlab-ci.yml

@@ -2,8 +2,6 @@
 image: rocker/tidyverse:4.4.0
 
 before_script:
-  - docker system prune -a -f
-  - docker builder prune -f
   - apt-get update
   - apt-get install -y --no-install-recommends libcurl4-openssl-dev libxext6 libxtst6 libxt6
   - apt-get install -y --no-install-recommends qpdf pandoc pandoc-citeproc