Issues with pythreejs with 6.4.0

Upgrading from `ipykernel==6.3.1` `ipykernel==6.4.0` breaks `pythreejs` when serializing any `pythreejs.OrbitControls`.

```
~/python/pyvista/pyvista/jupyter/pv_pythreejs.py in convert_renderer(pv_renderer)
494 )
495
--> 496 controls = [tjs.OrbitControls(controlling=camera)]
497
498 renderer = tjs.Renderer(camera=camera,

/tmp/venv/lib/python3.8/site-packages/pythreejs/controls/OrbitControls_autogen.py in __init__(self, controlling, **kwargs)
27 def __init__(self, controlling=None, **kwargs):
28 kwargs['controlling'] = controlling
---> 29 super(OrbitControls, self).__init__(**kwargs)
30
31 _model_name = Unicode('OrbitControlsModel').tag(sync=True)

/tmp/venv/lib/python3.8/site-packages/pythreejs/controls/Controls_autogen.py in __init__(self, **kwargs)
28
29 def __init__(self, **kwargs):
---> 30 super(Controls, self).__init__(**kwargs)
31
32 _model_name = Unicode('ControlsModel').tag(sync=True)

/tmp/venv/lib/python3.8/site-packages/pythreejs/_base/Three.py in __init__(self, **kwargs)
15
16 def __init__(self, **kwargs):
---> 17 super(ThreeWidget, self).__init__(**kwargs)
18 self.on_msg(self._on_potential_ret_val)
19

/tmp/venv/lib/python3.8/site-packages/ipywidgets/widgets/widget.py in __init__(self, **kwargs)
413
414 Widget._call_widget_constructed(self)
--> 415 self.open()
416
417 def __del__(self):

/tmp/venv/lib/python3.8/site-packages/ipywidgets/widgets/widget.py in open(self)
436 args['comm_id'] = self._model_id
437
--> 438 self.comm = Comm(**args)
439
440 @observe('comm')

/tmp/venv/lib/python3.8/site-packages/ipykernel/comm/comm.py in __init__(self, target_name, data, metadata, buffers, **kwargs)
55 if self.primary:
56 # I am primary, open my peer.
---> 57 self.open(data=data, metadata=metadata, buffers=buffers)
58 else:
59 self._closed = False

/tmp/venv/lib/python3.8/site-packages/ipykernel/comm/comm.py in open(self, data, metadata, buffers)
89 comm_manager.register_comm(self)
90 try:
---> 91 self._publish_msg('comm_open',
92 data=data, metadata=metadata, buffers=buffers,
93 target_name=self.target_name,

/tmp/venv/lib/python3.8/site-packages/ipykernel/comm/comm.py in _publish_msg(self, msg_type, data, metadata, buffers, **keys)
64 metadata = {} if metadata is None else metadata
65 content = json_clean(dict(data=data, comm_id=self.comm_id, **keys))
---> 66 self.kernel.session.send(self.kernel.iopub_socket, msg_type,
67 content,
68 metadata=json_clean(metadata),

/tmp/venv/lib/python3.8/site-packages/jupyter_client/session.py in send(self, stream, msg_or_type, content, parent, ident, buffers, track, header, metadata)
828 if self.adapt_version:
829 msg = adapt(msg, self.adapt_version)
--> 830 to_send = self.serialize(msg, ident)
831 to_send.extend(buffers)
832 longest = max([len(s) for s in to_send])

/tmp/venv/lib/python3.8/site-packages/jupyter_client/session.py in serialize(self, msg, ident)
702 content = self.none
703 elif isinstance(content, dict):
--> 704 content = self.pack(content)
705 elif isinstance(content, bytes):
706 # content is already packed, as in a relayed message

/tmp/venv/lib/python3.8/site-packages/jupyter_client/session.py in json_packer(obj)
93
94 def json_packer(obj):
---> 95 return jsonapi.dumps(
96 obj,
97 default=json_default,

/tmp/venv/lib/python3.8/site-packages/zmq/utils/jsonapi.py in dumps(o, **kwargs)
23 Keyword arguments are passed along to :py:func:`json.dumps`.
24 """
---> 25 return json.dumps(o, **kwargs).encode("utf8")
26
27

/usr/lib/python3.8/json/__init__.py in dumps(obj, skipkeys, ensure_ascii, check_circular, allow_nan, cls, indent, separators, default, sort_keys, **kw)
232 if cls is None:
233 cls = JSONEncoder
--> 234 return cls(
235 skipkeys=skipkeys, ensure_ascii=ensure_ascii,
236 check_circular=check_circular, allow_nan=allow_nan, indent=indent,

/usr/lib/python3.8/json/encoder.py in encode(self, o)
197 # exceptions aren't as detailed. The list call should be roughly
198 # equivalent to the PySequence_Fast that ''.join() would do.
--> 199 chunks = self.iterencode(o, _one_shot=True)
200 if not isinstance(chunks, (list, tuple)):
201 chunks = list(chunks)

/usr/lib/python3.8/json/encoder.py in iterencode(self, o, _one_shot)
255 self.key_separator, self.item_separator, self.sort_keys,
256 self.skipkeys, _one_shot)
--> 257 return _iterencode(o, 0)
258
259 def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,

ValueError: Out of range float values are not JSON compliant
```

Reason being is the `inf` in the orbit controls that was fine before the last update:
```
{'state': {'_model_module': 'jupyter-threejs', '_model_module_version': '^2.1.0', '_model_name': 'OrbitControlsModel', '_view_count': None, '_view_module': None, '_view_module_version': '', '_view_name': None, 'autoRotate': False, 'autoRotateSpeed': 2.0, 'controlling': 'IPY_MODEL_a205842466d44cf0a9bcd908a9c54253', 'dampingFactor': 0.25, 'enableDamping': False, 'enableKeys': True, 'enablePan': True, 'enableRotate': True, 'enableZoom': True, 'enabled': True, 'keyPanSpeed': 7.0, 'maxAzimuthAngle': inf, 'maxDistance': inf, 'maxPolarAngle': 3.141592653589793, 'maxZoom': inf, 'minAzimuthAngle': -inf, 'minDistance': 0.0, 'minPolarAngle': 0.0, 'minZoom': 0.0, 'panSpeed': 1.0, 'rotateSpeed': 1.0, 'screenSpacePanning': True, 'target': (0.0, 0.0, 0.0), 'zoomSpeed': 1.0}, 'buffer_paths': []}
```

I'm not sure if this something that needs to be fixed in `ipywidgets`, but I'm posting it here so there's a record of this issue.