publish_to_internal_channel is not threadsafe

Nadie ha tomado este issue todavía.

https://github.com/indeedeng/iwf-python-sdk/blob/a13c309d58bb553a3ee27c85899f7f25c500d877/iwf/communication.py#L51

Here's part of the publish_to_internal_channel func :
``` python
def publish_to_internal_channel(self, channel_name: str, value: Any = None):
...
vals = self._to_publish_internal_channel.get(channel_name)
if vals is None:
vals = []
vals.append(self._object_encoder.encode(value))
self._to_publish_internal_channel[channel_name] = vals
```
When multiple threads hitting this function, it could have a race condition where
Thread A gets vals = [1,2,3]
Thread B gets vals = [1,2,3]
Thread A updates it to be [1,2,3,4]
Thread B updates it to be [1,2,3,5]
Here we lost 4 permanently

Comienza en iwf/communication.py, en publish_to_internal_channel, y revisa cómo se lee y actualiza _to_publish_internal_channel. Añade cobertura para publicaciones concurrentes y verifica después que no se pierda ningún valor cuando varios hilos publican en el mismo canal.

Escrito por el modelo de indexación a partir del texto del issue.