Dcoraid

- feat: support new DCOR API for uploading data directly to S3
- feat: perform faster ETag verification instead of SHA256 summing
- enh: add api.errors.APIBadRequest error class
- enh: speed-up resource download by computing SHA256 while downloading
- enh: improve logging
- setup: bump dclab from 0.57.0 to 0.58.5
- setup: migrate from setup.py to pyproject.toml

- setup: bump dclab from 0.55.7 to 0.57.0

- setup: bump dclab from 0.52.0 to 0.55.7

- fix: handle not-found-errors for non-existent resource downloads
- ref: replace setuptools pkg_resources with importlib.resources

- setup: drop support for Python 3.9
- ci: migrate from appveyor to GitHub Actions

- fix: twisted error message upon SHA-256 upload verification (73)
- fix: user_show raised unexpected APINotFoundError in wizard
- fix: support None as empty API key
- fix: explain to user how to create API token, since CKAN 2.10 does
not support automatic generation of API keys anymore
- fix: workaround for broken CKAN logic in user_show
- enh: skip SSL verification via DCORAID_SKIP_SSL_VERIFY environment variable
- enh: add ``__repr__`` for ``CKANAPI``
- ref: introduce `CKANAPI.ckan_version_object` fetching the CKAN version