About page: Replace 3.7 with the current version (3.7.1, etc.).

Normally this would be sprintf'd in but we don't want to change a string at this point.

fixes #25683 for the 3.7 branch.

Built from https://develop.svn.wordpress.org/branches/3.7@25927


git-svn-id: http://core.svn.wordpress.org/branches/3.7@25886 1a063a9b-81f0-0310-95a4-ce76da25c4cd