[BUG] When using `extend`, the `@@map` is inherited as well

[dhritcu]

In case we use Polymorphism with @@map, the generated prisma schema is invalid.

Given the following zmodel:

model Foo {
  //...
  @@map("foos")
}

model Bar extends Foo {
  @@map("bars")
}

It will generate the following prisma

model Foo {
  //...
  @@map("foos")
}

model Bar {
  @@map("foos")
  @@map("bars")
}

And will output the following validation error when generating migrations.

error: Attribute "@map" can only be defined once.

[ymc9]

fixed in beta.9