The `like()` helper is case sensitive on PostgreSQL

[kblais]

The like() helper (https://github.com/kblais/query-filter/blob/master/src/QueryFilter.php#L84-L87) uses the SQL function LIKE.
On PostgreSQL, and unlike other database engines, LIKE is case sensitive. PostgreSQL offers the function ILIKE, which is case insensitive.

The behaviour should be consistent on any database engine, the case-insensitive being more logic.