fix a test that accidentally tried to serialize a Block

t/04-roundtrip.t

@@ -16,7 +16,7 @@ my @s =
         'Array of Str'   => [ <one two three gazooba> ],
         'Empty Hash'     => {},
         'Hash of Int'    => { :one(1), :two(2), :three(3) },
-        'Hash of Num'    => { :one-and-some{1}, :almost-pie(3.3) },
+        'Hash of Num'    => { :one-and-some[1], :almost-pie(3.3) },
         'Hash of Str'    => { :one<yes_one>, :two<but_two> },
         'Array of Stuff' => [ { 'A hash' => 1 }, [<an array again>], 2],
         'Hash of Stuff'  =>