ci: remove useless whitespace in the .gitlab-ci.yml

.gitlab-ci.yml

@@ -12,7 +12,7 @@ default:
 .check:
   stage: check
   script:
-  - R -e ' rcmdcheck::rcmdcheck(args = ifelse(as.logical(Sys.getenv("NOT_CRAN")), "", "--as-cran"), error_on = "error")'
+  - R -e 'rcmdcheck::rcmdcheck(args = ifelse(as.logical(Sys.getenv("NOT_CRAN")), "", "--as-cran"), error_on = "error")'
 
 .check_as_cran:
   variables: