Check for latest centos release version when doing a release
Check for latest centos release version when doing a release

Motivation:

We used to check for version 6.8 but the latest is 6.9

Modifications:

Update version to 6.9 in the check.

Result:

Be able to cut a release on latest centos version

imangry/netty-zh,imangry/netty-zh,imangry/netty-zh,imangry/netty-zh,imangry/netty-zh