Merge remote-tracking branch 'cgal/5.6.x-branch' into 'cgal/6.0.x-branch'

Author: sloriot

Straight_skeleton_extrusion_2/include/CGAL/extrude_skeleton.h

@@ -812,7 +812,7 @@ class Extrusion_builder
                                           CGAL_SS_i::vertices_begin(hole),
                                           CGAL_SS_i::vertices_end(hole),
                                           std::begin(no_holes), std::end(no_holes),
-                                          std::begin(speeds[hole_id]), std::end(speeds[hole_id]),
+                                          std::begin(speeds[1 + hole_id]), std::end(speeds[1 + hole_id]),
                                           std::begin(no_speeds), std::end(no_speeds),
                                           m_gt);