cant find blitz custom server

### What is the problem?

The custom server does not work as described in the docs😞

### Paste all your error logs here:

```
Cannot find module 'blitz/custom-server' or its corresponding type declarations.ts(2307)
```

### Paste all relevant code snippets here:

```
PASTE_HERE (leave the ``` marks)
```

### What are detailed steps to reproduce this?

1. install a new blitz app and try to put in the custom server example from the [docs](https://blitzjs.com/docs/custom-server)

### Run `blitz -v` and paste the output here:

```
Blitz version: 2.0.0-beta.17 (global)
Blitz version: 2.0.8 (local)
macOS | darwin-arm64 | Node: v18.16.0

Package manager: npm

System:
OS: macOS 14.4.1
CPU: (10) arm64 Apple M1 Pro
Memory: 338.44 MB / 32.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
Node: 18.16.0 - ~/.nvm/versions/node/v18.16.0/bin/node
Yarn: Not Found
npm: 9.5.1 - ~/.nvm/versions/node/v18.16.0/bin/npm
npmPackages:
@blitzjs/auth: 2.0.8 => 2.0.8
@blitzjs/next: 2.0.8 => 2.0.8
@blitzjs/rpc: 2.0.8 => 2.0.8
@prisma/client: 4.6.0 => 4.6.0
blitz: 2.0.8 => 2.0.8
next: 13.5.6 => 13.5.6
prisma: 4.6.0 => 4.6.0
react: 18.2.0 => 18.2.0
react-dom: 18.2.0 => 18.2.0
typescript: ^4.8.4 => 4.9.5
```

### Please include below any other applicable logs and screenshots that show your problem: