No valid runtime type for external library imports

`GraphQLClient` is a class.
```ts
import { GraphQLClient } from 'graphql-request';
typeOf<GraphQLClient>(); // Error: No valid runtime type for function GraphQLClient given. Is @deepkit/type-compiler correctly installed? Execute deepkit-type-install to check
```
It should be `{ kind: 1, typeName: 'GraphQLClient' }`.