hallettj has created PR #1003: fix: list_collections fails with MongoDB Atlas database with time-series collection in mongo-rust-driver

Issue Text:
When creating a time-series collection on MongoDB Atlas the `clusteredIndex` field of the collection options is given as `true` instead of as an object that deserializes to `ClusteredIndex`. The rust driver does not expect a boolean in that position, so parsing `CreateCollectionOptions` fails. This causes methods such as `db.list_collections()` to fail.

This change adds a custom deserializer that handles the case where `clusteredIndex: true` by filling in the default value for `ClusteredIndex`.

I don't know if `clusteredIndex: false` is a valid state so in the interest of being conservative I have made that an error case in the custom deserializer.