tokio-postgres is not supported by hyperdrive, but the doc says it can be used

### Existing documentation URL(s)

- https://developers.cloudflare.com/hyperdrive/examples/connect-to-postgres/#supported-drivers

### What changes are you suggesting?

https://github.com/cloudflare/workers-sdk/issues/13798#issuecomment-4420362234

`tokio-postgres` is not supported. And in fact, it's not usable in many cases, for example, connection will be closed if there's CTE or user-defined type (I cannot ensure which is the real reason in my practice).

(EDIT: it's user-defined type leads hyperdrive shutdown the connection)

Maybe it should be removed or marked as highly unrecommended.

### Additional information

_No response_