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- pymongo 4+ no longer executes operations after `MongoClient`` is closed.
As a result, the `Mongo` backend will now return a `list` from the context
manager to prevent the following error:
pymongo.errors.InvalidOperation: Cannot use MongoClient after close
- https://pymongo.readthedocs.io/en/stable/migrate-to-pymongo4.html#mongoclient-cannot-execute-operations-after-close