Wrong expected type in class `Goal` from lida/datamodel.py

[goldiusleonard]

Once I run the sample code for extracting charts, I encountered a problem of different expected type for visualisation variable in class Goal. Please change the expected type of the variable from str to dict. Thank you!

[victordibia]

@trojrobert , any chance you want to open a PR for this?

[trojrobert]

@victordibia Ok, I will look into it