Keystone cli installs conflicting versions of prisma dependencies

Out of the box, `keystone dev` installs `@prisma/client` and `prisma` dependencies in such a way that version conflicts arise.

1. Perform "install" walkthrough
2. Run `keystone dev`

You'll see an error message which indicates a version mismatch of prisma dependencies:

```
Error: @prisma/client did not initialize yet. Please run "prisma generate" and try to import it again.
```

**Expected:**
Keystone works out of the box. Keystone CLI should install the packages locally with the same version specifier as its internal `package.json`.

**Additional Info**
``` shell
$ pnpm why @prisma/client

dependencies:
@keystone-6/core 6.3.0
└── @prisma/client 5.19.0
@prisma/client 5.20.0
```

Start with the `keystone dev` command and the dependency installation used by the install walkthrough; run `pnpm why @prisma/client` to inspect the conflicting versions. Done means the CLI installs matching Prisma dependency versions and the walkthrough runs without requiring a manual `prisma generate` step.

Written by the indexing model from the issue text.