Avoid using readarray in our fake stub ruby due to GitHub Action's macOS.

Author: postmodern

test/setup

@@ -32,9 +32,7 @@ if [[ "\$1" == "-e" ]]; then
 			;;
 	esac
 else
-	readarray -t input
-
-	for line in "\${input[@]}"; do
+	while IFS=$'\n' read -r line; do
 		if [[ "\$line" == *"puts \"export RUBY_ENGINE=#{Object.const_defined?(:RUBY_ENGINE) ? RUBY_ENGINE : 'ruby'};\""* ]]; then
 			echo "export RUBY_ENGINE=$test_ruby_engine;"
 		fi