Issue #3214921 by daffie, xurizaemon, alexpott, mondrake, andypost, Taran2L,...
Issue #3214921 by daffie, xurizaemon, alexpott, mondrake, andypost, Taran2L, Mixologic, longwave: Add a requirements warning in Drupal 9 when PostgreSQL is used and the pg_trgm extension is not created