Use double for cpnest parameter

The fix in !888 (merged) didn't actually fix the implementation for CBCs. The GPS times we use don't fit inside the float that was being used. This MR makes sure we use a double, which will hopefully be large enough for the foreseeable future.

bilby/core/sampler/cpnest.py

@@ -89,8 +89,8 @@ class Cpnest(NestedSampler):
                 prior_samples = self.priors.sample()
                 self._update_bounds()
                 point = LivePoint(
-                    self.names, array.array(
-                        'f', [prior_samples[name] for name in self.names]))
+                    self.names, array.array('d', [prior_samples[name] for name in self.names])
+                )
                 return point
 
         self._resolve_proposal_functions()