Use a more robust way to get dco-win version

Use a more robust way to get dco-win version

The current way doesn't work if the device is already in use.

Starting from 1.3.0, dco-win creates a non-exclusive
control device \\.\ovpn-dco-ver which can be opened by
multiple apps and supports a single IOCTL to get
a version number.

https://github.com/OpenVPN/ovpn-dco-win/pull/76

This will be expecially handy later when checking which
features driver supports.

Change-Id: Ieb6f3a9d14d76000c1caf8ee1e959c6d0de832bf
Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20240809192257.24208-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29009.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>