Eliminated remaining PriorSet references

CHANGELOG.md

bilby/core/prior.py

bilby/core/result.py

bilby/core/sampler/__init__.py

bilby/core/sampler/base_sampler.py

bilby/gw/likelihood.py

examples/injection_examples/australian_detector.py

examples/injection_examples/basic_tutorial.py

examples/injection_examples/binary_neutron_star_example.py

examples/injection_examples/change_sampled_parameters.py

examples/injection_examples/eccentric_inspiral.py

examples/injection_examples/how_to_specify_the_prior.py

examples/injection_examples/marginalized_likelihood.py

examples/injection_examples/plot_skymap.py

examples/open_data_examples/GW150914.py

examples/open_data_examples/GW150914_minimal.py

test/gw_likelihood_test.py

test/gw_prior_test.py

test/prior_test.py

test/result_test.py