Just make your application create the indexes explicitly, instead of generating SQL that causes these warnings.

# code like this causes the notice you listed
CREATE TABLE foo (
  id char(32) unique
);

# if you don't want the notice, don't let it create
# implicit indexes, create them yourself explicitly
CREATE TABLE foo (
  id char(32)
);
ALTER TABLE ONLY foo
    ADD CONSTRAINT foo_id_key UNIQUE (id);
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