Ckanext-dc-view

- fix: use "deform" for datasets that don't have "bright_avg"
in preview

- ref: move to dcor_shared 0.2.5

- enh: add a ``job_id`` to the "preview" background job and,
depending on whether or not the ckanext-dc_serve extensions is
installed, wait for the "condense" background job before
attempting to create a preview image; this avoids computing
the brightness twice (2)

- fix: manifest did not include .yml

- maintenance release

- maintenance release