openssh: bump version

From the announcement:

This release fixes a security bug:

 * sshd(8): fix a memory corruption problem triggered during rekeying
   when an AES-GCM cipher is selected. Full details of the vulnerability
   are available at: http://www.openssh.com/txt/gcmrekey.adv



Signed-off-by: Peter Korsgaard <peter@korsgaard.com>