Optional fields should use nullable instead of nullish

[arielpacciaroni]

If I got the following model:

model User {
  /// other fields
  name    String?
}

It should produce the following zod schema:

const UserSchema = z.object({
  name: z.string().nullable()
})

instead of:

const UserSchema = z.object({
  name: z.string().nullish()
})

I believe that string | null union type (from Prisma exports) suits better than string | undefined | null union type got from Zod schemas

[BirdLeeSCUT]

+1, it would be more cosistent