Add dc terms date

https://www.dublincore.org/specifications/dublin-core/dcmi-terms/#http://purl.org/dc/elements/1.1/date

Author: abetwothree

src/Detectors/PublishedTime.php

@@ -38,7 +38,8 @@ public function detect(): ?Datetime
                 'rc.datecreation',
                 'timestamp',
                 'sailthru.date',
-                'article:modified_time'
+                'article:modified_time',
+                'dcterms.date'
             );
     }