GHA: Use CMake 4.0 and apply required fixes

GHA: Use CMake 4.0 and apply required fixes

- update vcpkg reference to 856505bb76
  This includes a general work-around for the CMake 4.0
  compat. See commit
  a1aebfa9d5eae7cf493e0a706b43915d687bb860.
- update lukka/get-cmake action to v4
- update dependency aws/aws-lc to v1.49.1

Change-Id: Ibabb4aa80d7786614dbd6b76bd4cd096f217acfd
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Yuriy Darnobyt <yura.uddr@gmail.com>
Message-Id: <20250409131148.18147-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31399.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>