upgrade builtin SoQt version from 1.6.0 to 1.6.2
Proposing to upgrade the builtin SoQt version (1.6.0 -> 1.6.2) to make it possible to build against Qt6, which didn't work with the current version predating https://github.com/coin3d/soqt/pull/67
Checked to work with GeoModel 5.3.0.
Edited by Julien Maurer