Error with composite foreign keys when importing from PostgreSQL

[FergusFettes]

Duplicate of #142 but for Postgres.

Example Postgres Import:

create table table1 (
    field text not null,
    field2 text not null,
    primary key(field, field2)
);

create table if not exists table2 (
    id int generated always as identity primary key,
    field text,
    field2 text,
    foreign key (field, field2) references table1(field, field2)
);

using the web interface.

[NQPhuc]

Fixed in #416