Lab: Suppress warning

[afabri]

Summary of Changes

Suppress warning issued by gcc.

include/CGAL/Three/Viewer_interface.h:42:21: warning: defining ‘CGAL::Three::Viewer_interface’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
   42 | class VIEWER_EXPORT Viewer_interface : public CGAL::QGLViewer{
      |                     ^~~~~~~~~~~~~~~~

Release Management

• Affected package(s): Lab
• License and copyright ownership: unchanged