Does not support `citext[]` in postgres

[cflipse]

Describe the bug

In postgres, citext arrays (citext[]) are not supported consistantly with text arrays (text[]). Both types should be usable.

Currently, text[] is supported as expected; when values are retreived, they are exposed to ruby as string arrays: ["one", "two", "three four"]. citext[] does not perform this same translation; instead results are returned in a native format: '{"one", "two", "three four"}'

Examining the inferred schema gives no indication of why they behave differently: text[]:

=> #<ROM::SQL::Attribute[NilClass | Array] name=:tags db_type="text[]" database="postgres" type="text" read=#<Dry::Types[Sum<Constrained<Nominal<NilClass> rule=[type?(NilClass)]> | Constructor<Array fn=/home/flip/.gem/ruby/2.6.4/gems/rom-sql-3.0.1/lib/rom/sql/extensions/postgres/types/array.rb:13>>]> source=ROM::Relation::Name(products) index=true qualified=true sql_expr=#<Sequel::SQL::QualifiedIdentifier @table=>:products, @column=>:tags> alias=nil>

citext[]:

#<ROM::SQL::Attribute[NilClass | Array] name=:tags db_type="citext[]" database="postgres" type="citext" read=#<Dry::Types[Sum<Constrained<Nominal<NilClass> rule=[type?(NilClass)]> | Constructor<Array fn=/home/flip/.gem/ruby/2.6.4/gems/rom-sql-3.0.1/lib/rom/sql/extensions/postgres/types/array.rb:13>>]> source=ROM::Relation::Name(products) index=true qualified=true sql_expr=#<Sequel::SQL::QualifiedIdentifier @table=>:products, @column=>:tags> alias=nil>

To Reproduce

• generate a postgres table with citext extension enabled.
• create a table with text[] and citext[] columns
• use an relation with inferred schema
• add an array to both colums; note the difference in read results

Expected behavior citext[] should behave the same as text[]