python3: convert `dict_keys` to list for python2.

cinema_python/adaptors/paraview/pv_introspect.py

@@ -711,7 +711,7 @@ def explore(cs, proxies, iSave=True, currentTime=None, userDefined={},
     dist = paraview.simple.GetActiveCamera().GetDistance()
 
     # associate control points with parameters of the data store
-    params = cs.parameter_list.keys()
+    params = list(cs.parameter_list.keys())
     tracks = []
     if camType == "phi-theta":
         up = [math.fabs(x) for x in view_proxy.CameraViewUp]