Change to install past Rubygems and Bundler if less than Ruby 2.6

https://github.com/rubygems/rubygems/releases/tag/bundler-v2.4.0
https://github.com/rubygems/rubygems/releases/tag/v3.4.0

Author: ydah

script/predicate_functions.sh

@@ -57,6 +57,14 @@ function is_mri_2plus {
   fi
 }
 
+function is_ruby_26_plus {
+  if ruby -e "exit(RUBY_VERSION.to_f >= 2.6)"; then
+    return 0
+  else
+    return 1
+  fi
+}
+
 function is_ruby_23_plus {
   if ruby -e "exit(RUBY_VERSION.to_f >= 2.3)"; then
     return 0

script/update_rubygems_and_install_bundler

@@ -5,9 +5,13 @@
 set -e
 source script/functions.sh
 
-if is_ruby_23_plus; then
+if is_ruby_26_plus; then
   gem update --no-document --system
   gem install --no-document bundler
+elif is_ruby_23_plus; then
+  echo "Warning installing older versions of Rubygems / Bundler"
+  gem update --system '3.3.26'
+  gem install bundler -v '2.3.26'
 else
   echo "Warning installing older versions of Rubygems / Bundler"
   gem update --system '2.7.10'