Heroku rake db:migrate aborted with 'PG::Error:'
It's attempting to populate the database from you schema. The problem is that it's trying to add comments to a postgresql extension that your database user does not own. These 3 lines will cause problems:
COMMENT ON EXTENSION plpgsql IS 'PL/pgSQL procedural language';COMMENT ON EXTENSION pg_trgm IS 'text similarity measurement and index searching based on trigrams';COMMENT ON EXTENSION unaccent IS 'text search dictionary that removes accents';In order to comment on any database object, you need to be the owner of that object. See the PostgreSQL documentation for more information.
Heroku also doesn't allow you to create or modify extensions. They provide a list of available extensions and text-search dictionaries that are available for use and all of the extensions in your schema dump are listed.
Remove or comment out the lines code in the schema dump that are creating extensions and creating comments on extensions and that should get you past that error.