change echo to printf for portability

Author: jazzsequence

tests/run-test.sh

@@ -43,5 +43,5 @@ if ! diff <(echo "$ACTUAL_OUTPUT") <(echo "$EXPECTED_OUTPUT") > /dev/null; then
 fi
 
 echo "RESULT: PASSED ✅"
-echo -e "\n"
+printf "\n"
 exit 0