Sonar-scanner version compatibility with sonarqube 7.9

We have recently migrated our sonarqube 7.1 to 7.9 and it is showing proper version on GUI.
But we want to confirm that which sonar-scanner will be compatible with 7.9
As of now we are using SonarQube Scanner 2.8.
Plus we are getting below error while running sonar-scanner -


As a rule, you should always take the scanner upgrade if one is available. The current scanner version is 4.4, so you’re quite a ways behind. You should upgrade at your earliest convenience.