Update scripts to run compat specs against Rails 6

Author: pirj

travis/script/predicate_functions.sh

@@ -54,8 +54,8 @@ function is_mri_2plus {
   fi
 }
 
-function is_ruby_23_plus {
-  if ruby -e "exit(RUBY_VERSION.to_f >= 2.3)"; then
+function is_ruby_25_plus {
+  if ruby -e "exit(RUBY_VERSION.to_f >= 2.5)"; then
     return 0
   else
     return 1
@@ -75,7 +75,7 @@ function is_mri_27 {
 }
 
 function rspec_rails_compatible {
-  if is_ruby_23_plus; then
+  if is_ruby_25_plus; then
     return 0
   else
     return 1

travis/script/update_rubygems_and_install_bundler

@@ -2,7 +2,7 @@
 set -e
 source script/functions.sh
 
-if is_ruby_23_plus; then
+if is_ruby_25_plus; then
   yes | gem update --system
   yes | gem install bundler
 else