only install remotes if not avail; upgrade as needed

Author: nmdefries

.github/workflows/r-ci.yml

@@ -52,8 +52,11 @@ jobs:
             install.packages("devtools")
             devtools::install_version("readr", version = "1.4.0")
           }
-          install.packages("remotes")
-          remotes::update_packages(c("rcmdcheck", "mockr"), upgrade="always")
+
+          if ( !require("remotes") ) {
+            install.packages("remotes")
+          }
+          remotes::update_packages(c("rcmdcheck", "mockr", "remotes"), upgrade="always")
           dependency_list <- remotes::dev_package_deps(dependencies=TRUE)
           remotes::update_packages(dependency_list$package[dependency_list$package != "readr"], upgrade="always")
         shell: Rscript {0}