Standardizes shebang and coding declarations.
Coding matches what's used by install tools such as pip(x).
Removes a few init files that were not needed.
Lint with [refurb](https://github.com/dosisod/refurb) using `--disable 126 --python-version 3.9`
Also update bats to 1.8.2 and bats-assets to 2.1.0. No changes to the tests, all still passing.