The raw BSON serializer currently does not implement the is_human_readable method from the Serializer trait, and the default implementation returns true. This is inaccurate, however, for raw BSON, which is not human readable, and it's also inconsistent with the raw BSON deserializer, which does return false from this method's equivalent. We should update the serializer to indicate that raw BSON is not human readable.

According to the serde docs, changing this value should be considered a breaking change, so we'll need to do this for the 2.0.0 release.