Publish properly on PyPI

[soxofaan]

I just pushed a recent build to PyPI at https://pypi.org/project/openeo-aggregator/ to reserve this package name there

some next steps here

• make sure project has proper description
• automate build+test+publish in some way?
• finetune build metadata, e.g. replace setup.py with pyproject.toml (Switch to pyproject.toml  #116), link to docs (see Start EOEPCA 'federated orchestrator' documentation repo #142 ) ...