3.0 Deprecation Warnings: Action TrackerStore deprecations

[ancalita]

Background
These warnings were found in:

• rasa.core.tracker_store.py:L99

"f""Specifying the `retrieve_events_from_previous_conversation_sessions` ""
f""kwarg for the `{self.__class__.__name__}` class is deprecated and ""
f""will be removed in Rasa Open Source 3.0. ""
f""Please use the `retrieve_full_tracker()` method instead."""

• rasa.core.tracker_store.py:L269

"f""Found pickled tracker for ""
 f""conversation ID '{sender_id}'. Deserialization of pickled ""
f""trackers is deprecated and will be removed in Rasa Open Source 3.0. Rasa ""
 f""will perform any future save operations of this tracker using json ""
f""serialisation."""

Definition of Done:

• resolve warnings in 3.0

[joejuzl]

Also found this one in DynamoTrackerStore:

    def save(self, tracker: DialogueStateTracker) -> None:
        """Saves the current conversation state."""
        from botocore.exceptions import ClientError

        if self.event_broker:
            self.stream_events(tracker)
        serialized = self.serialise_tracker(tracker)

        try:
            self.db.put_item(Item=serialized)
        except ClientError as e:
            if "Missing the key session_date" in repr(e):
                # the session_date attribute got removed as it was useless
                # old databases will still contain an attribute for it though
                # which we need to set (otherwise we are getting the error we
                # just ran into) this section should be removed in 3.0
                legacy_date = self._retrieve_latest_session_date(tracker.sender_id)

                serialized["session_date"] = legacy_date
                self.db.put_item(Item=serialized)
            else:
                raise