[MISC] Extend relation-user listing syntax (#868)

Author: sinclert-canonical

lib/charms/postgresql_k8s/v0/postgresql.py

@@ -35,7 +35,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 51
+LIBPATCH = 53
 
 # Groups to distinguish HBA access
 ACCESS_GROUP_IDENTITY = "identity_access"
@@ -672,7 +672,9 @@ def list_users_from_relation(self) -> Set[str]:
         try:
             with self._connect_to_database() as connection, connection.cursor() as cursor:
                 cursor.execute(
-                    "SELECT usename FROM pg_catalog.pg_user WHERE usename LIKE 'relation_id_%';"
+                    "SELECT usename "
+                    "FROM pg_catalog.pg_user "
+                    "WHERE usename LIKE 'relation_id_%' OR usename LIKE 'relation-%';"
                 )
                 usernames = cursor.fetchall()
                 return {username[0] for username in usernames}