openvpn: update to 2.6.11

openvpn: update to 2.6.11

This is a bugfix release containing several security fixes.

Security fixes
--------------
 - CVE-2024-4877: Windows: harden interactive service pipe.
   Security scope: a malicious process with "some" elevated privileges
   could open the pipe a second time, tricking openvn GUI
   into providing user credentials (tokens),  getting full access
   to the account openvpn-gui.exe runs as.

 - CVE-2024-5594: control channel: refuse control channel messages
   with nonprintable characters in them.
   Security scope: a malicious openvpn peer can send garbage to openvpn log,
   or cause high CPU load.

 - CVE-2024-28882: only call schedule_exit() once (on a given peer).
   Security scope: an authenticated client can make the server "keep the session"
   even when the server has been told to disconnect this client

Bug fixes
---------
 - fix connect timeout when using SOCKS proxies

 - work around LibreSSL crashing on OpenBSD 7.5 when enumerating ciphers

 - Add bracket in fingerprint message and do not warn about missing verification

For details refer to https://github.com/OpenVPN/openvpn/blob/v2.6.11/Changes.rst

Signed-off-by: Ivan Pavlov <redacted>