Install postgres extension with schema

I am trying to install pgcrypto in pg_catalog schema. But this does not work with postgres 13 or higher since the function gen_random_uuid is globally available. How can I still create my extension?

I am trying:

CREATE EXTENSION IF NOT EXISTS "pgcrypto" WITH SCHEMA pg_catalog CASCADE

I get the error:

ERROR: function "gen_random_uuid" already exists with same argument types.