Fix to handle new version of networkx
Fix to handle new version of networkx

ankurankan/pgmpy,kris-singh/pgmpy,sandeepkrjha/pgmpy,jhonatanoliveira/pgmpy,pgmpy/pgmpy,pgmpy/pgmpy,khalibartan/pgmpy,kris-singh/pgmpy,abinashpanda/pgmpy,abinashpanda/pgmpy,ankurankan/pgmpy,khalibartan/pgmpy,jhonatanoliveira/pgmpy,sandeepkrjha/pgmpy