Trained parameters are not loaded from state file.

[eirrgang]

The initialization from state.json has a gross oversight when loading pair paramters.

brer-md/src/brer/run_data.py

Line 336 in 18dab9d

pair_params = {name: PairParams(name=name, sites=fields['sites']) for name, fields in

should be changed to

            pair_params = {name: PairParams(name=name, **fields) for name, fields in

@carolinedav has an example state file that was not restored properly. We can use it as the basis for an improved test of the run_data module.