update sql script

conf/evolutions/default/95.sql

@@ -9,14 +9,14 @@ ALTER TABLE IF EXISTS users
 ALTER COLUMN avatar_url SET DEFAULT '/assets/images/user_no_image.png',
 ALTER COLUMN avatar_url SET NOT NULL;
 
--- Add a CHECK constraint to ensure avatar_url is not empty
+-- Add a CHECK constraint to ensure avatar_url is a string (TEXT type)
 ALTER TABLE IF EXISTS users
-ADD CONSTRAINT check_avatar_url_not_empty CHECK (avatar_url <> '');
+ADD CONSTRAINT check_avatar_url_is_string CHECK (pg_typeof(avatar_url) = 'text');
 
 -- --- !Downs
 -- Remove the CHECK constraint
 ALTER TABLE IF EXISTS users
-DROP CONSTRAINT IF EXISTS check_avatar_url_not_empty;
+DROP CONSTRAINT IF EXISTS check_avatar_url_is_string;
 
 -- Revert the avatar_url column to allow null values and remove the default value
 ALTER TABLE IF EXISTS users