ci: clone entire repo in publish workflow

parser: remove test code that wasn't meant to be pushed

version: bump to 0.8.3

i really gotta remember to start doing this BEFORE i push an update...

poetry: update lockfile

parser: make some functions/variables private

- These aren't meant to be available in the API.

[tests] Don't run tests on Python 3.7 anymore

[CLI] Add missing import

Bump version to 0.6.3

[parser] Update IM4PData.__repr__

Update version to 0.6.1