Merge pull request #10 from s-sajid-ali/cleanup_and_ci

update README

update README

change badge to use GithubActions output instead of travisCI

CI: bump tool setup python

versioning make explicit instead of vague

Update openpmd_updater/cli.py

CI: add requests requirement for tests

Fix CI

CI with Github Actions

tests to pytest, need pytest-order to ensure that read checks happen before files are transformed!

pyproject.toml: Add authors

minor

Transforms are optional, skip if no related components!

Use files from openPMD/openPMD-example-datasets repo directly