gen_random_uuid() is immutable in Pg 13devel

Hi,
I noticed that get_random_uuid() from pgcrypt is marked as immutable.

Up to 12.2 it was volatile, and in 13 it became immutable.

This leads to "interesting" change, that:

select gen_random_uuid() from generate_series(1,10);

returns 10 different uuids before 13, and 10 identical ones on 13devel.

It looks that commit 5925e5549890416bcf588334d9d0bc99f8ad6c7f forgot to
mark the function as volatile. Not sure if it was intentional.

Best regards,

depesz