unstructured

bfba2bb1 - fix: workaround .json file detection with old libmagic installs (#493)

fix: workaround .json file detection with old libmagic installs (#493) Fixes issue where .json files were recognized as "text/plain" rather than "application/json on the Unstructured image (and other installs that may have an older libmagic). Also adds missing json auto partition tests. Including an xfail test for #492 .