Ingest rank score to Arize (#552)

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# Description
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illustrations where appropriate. -->
Ranking score is currently not ingested to Arize, despite being present
in the dataframe.

# Modifications
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Add ranking score to the Arize Schema

# Tests
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# Checklist
- [ ] Added PR label
- [ ] Added unit test, integration, and/or e2e tests
- [ ] Tested locally
- [ ] Updated documentation
- [ ] Update Swagger spec if the PR introduce API changes
- [ ] Regenerated Golang and Python client if the PR introduces API
changes

# Release Notes
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```release-note

```

python/observation-publisher/publisher/observation_sink.py

@@ -101,6 +101,7 @@ def _to_arize_schema(self) -> Tuple[ArizeModelType, ArizeSchema]:
             model_type = ArizeModelType.REGRESSION
         elif isinstance(prediction_output, RankingOutput):
             schema_attributes = self._common_arize_schema_attributes() | dict(
+                prediction_score_column_name=prediction_output.rank_score_column,
                 rank_column_name=prediction_output.rank_column,
                 prediction_group_id_column_name=self._inference_schema.session_id_column,
             )