I been wanting to buy Honey Hex Freamework but

We simply do not check for the compatibility. It is possible that some parts would be no longer compatible, but with such a small version difference I think it should not be anything large. So it all depends how comfortable you feel with potential corrections to the code based on changes in unity. All core features are still avaliable in 2017.3 so the differences could be in some shader implementations/ interfaces etc. Its also possible it simply still works as it should, but we cannot guarantee that.