package/openvpn: bump version to 2.6.5
Changelog:
https://github.com/OpenVPN/openvpn/blob/release/2.6/ChangeLog
https://github.com/OpenVPN/openvpn/blob/release/2.6/Changes.rst
Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>