FORMAT: enforce isinstance type checking

bilby/bilby_mcmc/sampler.py

bilby/core/sampler/base_sampler.py

bilby/core/sampler/cpnest.py

bilby/core/utils/log.py

bilby/gw/detector/networks.py

bilby/gw/eos/eos.py

test/core/likelihood_test.py

test/core/prior/joint_test.py

test/gw/likelihood_test.py