Changes are inline:

- Support FILTER + WITHIN GROUP for aggregate expressions
- Comma separate the column names provided to RETURNING

- Update docs to add syntax for setting multiple [k, v] pairs ON CONF…

…LICT

- Add support for CREATE / DROP EXTENSION
- Add support for DISTINCT ON
- Include honeysql-posgres.format directly into honeysql-postgres.helpers to avoid leaking the require to the consumer
- Stop using lein and shift to deps exclusively
- Add CI and release/publish workflow
- Add support for testing all examples in the README as part of CI