Now passes an array.array object in the Cpnest livepoint constructor

Due to a recent update of cpnest, the sampler tests are currently failing

self = <bilby.core.sampler.cpnest.Cpnest.run_sampler.<locals>.Model object at 0x7f84f8c31f50>
    def new_point(self):
        """Draw a point from the prior"""
        prior_samples = self.priors.sample()
        self._update_bounds()
        point = LivePoint(
            self.names, [prior_samples[name]
>                        for name in self.names])
E       TypeError: Argument 'd' has incorrect type (expected array.array, got list)
bilby/core/sampler/cpnest.py:92: TypeError

This MR fixes it.