[hyperdrive] connection closed if there's user-defined type in sql (postgreSQL)

### What versions & operating system are you using?

```sh
System:
OS: Linux 7.0 Arch Linux
CPU: (12) x64 Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
Memory: 4.31 GB / 15.33 GB
Container: Yes
Shell: 4.7.1 - /usr/bin/fish
Binaries:
Node: 26.2.0 - /usr/bin/node
npm: 11.16.0 - /usr/bin/npm
npmPackages:
wrangler: ^4.95.0 => 4.98.0
```

### Please provide a link to a minimal reproduction

https://github.com/kingwingfly/cf_worker_hyperdrive_bug_report

### Describe the Bug

I'm using Rust `tokio-postgres` to work with `hyperdrive` + postgresql. And I'll binding user-defined type to the sql.

However, it's simply raise an error: `connection closed`.

The details are in the minimal reproduction.

### Please provide any relevant error logs

Error from console log:
```json
{
"level": "error",
"message": "pg connection error: connection closed"
// ...
}
```