This is a bug in the version check on 1.5.10.2482, not in your install. Your version is current, and you can ignore the banner.

The check takes the first tag in GitHub’s tag list as the latest stable release. Newer tags (an archive tag and the 1.6.0 release candidates) now sort ahead of 1.5.10.2482, so every stable install shows this warning.

The fix is merged to dev-branch (https://github.com/FOGProject/fogproject/pull/1823). It asks fogproject.org for the current versions instead. It ships in the next stable release.