fix: excludes constraints which aren't primary keys

The previous version of this file was returning all columns which had unique constraints. This change excludes these columns unless they are primary keys

Author: kiwicopple

src/lib/sql/primary_keys.sql

@@ -15,3 +15,4 @@ WHERE
   AND pg_class.relnamespace = pg_namespace.oid
   AND pg_attribute.attrelid = pg_class.oid
   AND pg_attribute.attnum = ANY (pg_index.indkey)
+  AND indisprimary