Ensure newline characters a then end of `.json` files are removed

In dbt-core we have a pre-commit hook which removes newline characters at the end of json files. We don't have that in schemas.getdbt.com. This sometimes means that a newline character exists in schemas.getdbt.com's version of jsonschema files, while core's never do. This causes a problem because in core we do a strict artifact comparison check to make sure things match. To resolve this, we should start enforcing the removal of newline characters in this repository.