Update InitGui.py

[Grubuntu]

• Fix problem when adding Workbenches that doesn't exist in other version of FreeCAD to the pie menu and try to use/modify it in an other FreeCAD version where the WB doesn't exist: AssemblyWB exists in 0.22 but not in 0.21. https://forum.freecad.org/viewtopic.php?t=84101&start=100#p747497
• Update translations