Enable check on the previous minor R release

closes #38

.gitlab-ci.yml

@@ -9,10 +9,10 @@
     - R -e 'devtools::install_deps()'
     - R -e 'devtools::check(error_on = "warning")'
 
-# # latest version of the previous major R release
-# check-previous:
-#   image: rocker/tidyverse:3.5.3
-#   <<: *check_job_template
+# latest version of the previous minor R release
+check-previous:
+  image: rocker/tidyverse:3.5.3
+  <<: *check_job_template
 
 # latest R release
 check-latest: