fix scan vertex index for prop value

[wey-gu]

close #218

From:

nebula-python/nebula3/sclient/BaseResult.py

Line 78 in 800f0f9

tag.props[self._col_names[index]] = self._row.values[index]

we could see the index was mismatched:

(Pdb) self._row.values
[Value(sVal=b'player112'), Value(sVal=b'player112'), Value(sVal=b'Jonathon Simmons'), Value(iVal=29)]
(Pdb) self._col_names
[b'_vid', b'name', b'age']