[joss-review] Add testing

[zonca]

It would be useful to have a way of testing the package.

Already we can run the example and verify if the package runs, but we do not know if the results make sense.

I think the easiest way would be to add a script in the analysis phase of the example run:
https://bayeseor.readthedocs.io/en/latest/usage.html#analyzing-bayeseor-outputs

this should check that the results are reasonable, for example checking the average value of some parameters and making sure they agree with the expected values with some assert statements.