make main31Vincia.cxx compile for Py8.309

Ewelina Maria Lobodzinskarequested to merge
ewelina-master-patch-14182 into master

In Pythia8.309 the functionality of PowhegHooksVicia.h has been moved to PowhegHooks.h In this MR some changes are introduced to make main31Vincia.cxx compile for both Py8.309 and old versions

Merge request reports