formatter: addition of format.mime_type column
formatter: addition of format.mime_type column

* Adds upgrade for the `Format` table by adding `mime_type`.

Signed-off-by: Konstantinos Kostis <237b836d1007d10b89d97a8c1749c99bbd9efc26@cern.ch>

tiborsimko/invenio-search,tiborsimko/invenio-search,inveniosoftware/invenio-search,inveniosoftware/invenio-search