ABC Parameter Estimation input data types

[wardo5]

When running the ABC Parameter Estimation with PyGOM, it seems to only work with a numpy dataframe, and doesn't accept a pandas dataframe as input.

Converting pandas dataframe using .to_numpy() corrects this error, but it would be useful to have a note in the documentation to specify that numpy dataframes must be used, or even better if the approximate_bayesian_computation in PyGOM could handle pandas data.