Pytest-invenio

- Adds support for OpenSearch v2

- Use invenio-search v2 and replaces Elasticsearch with OpenSearch, including
fixture names.
- Deprecate previous fixtures named with `es` prefix.
- Remove upper pin of pytest.

- Pin docker-services-cli<0.5.0, which drops Elasticsearch v6.

- Fix pycodestyle dependency

- Fix flask-login dependency