Parser does not handle version 14 function syntax

[davecramer]

New syntax for function definition allows functions to be defined without $$

CREATE OR REPLACE FUNCTION asterisks(n int)
  RETURNS SETOF text
  LANGUAGE sql IMMUTABLE STRICT PARALLEL SAFE
BEGIN ATOMIC
SELECT repeat('*', g) FROM generate_series (1, n) g; -- <-- Note this semicolon
END;

See #2506 for a reproducer