Update downstream applications

[tomkralidis]

Description

Given #937, we need to ensure that once pycsw 3.0.0 is released, that the following downstream applications are updated to cover breaking changes (i.e. YAML configuration) and use new features (i.e. OGC API - Records support):

• GeoNode
• CKAN

[kalxas]

GeoNode/geonode#10380

[ridoo]

GeoNode has already integrated v3.0.0-beta1 via GeoNode/geonode#13112

[kalxas]

pycsw is not in CKAN or ckanext-spatial requirements.
OWSLib is directly used in ckanext-spatial to interact with CSW servers:
https://github.com/ckan/ckanext-spatial/blob/master/requirements.txt#L11-L12

There is a reference on how to use pycsw externally to harvest the CKAN API:
https://github.com/ckan/ckanext-spatial/blob/master/doc/csw.md