feat: Update exporting media type

Previously this function assumed that media_type was something like
'HTML', but now it is mapped to the actual media_type, e.g.
'application/html'. See media_type_mapping.yaml in
ckanext-switzerland-ng for a full mapping of media types.

ckanext/dcatapchharvest/profiles.py

@@ -1079,13 +1079,12 @@ def _format_and_media_type_to_graph(self, resource_dict, distribution):
 
         # Export media type if it matches IANA media type vocabulary
         if resource_dict.get('media_type'):
-            lowercase_media_type_value = \
-                resource_dict.get('media_type').lower()
-            if lowercase_media_type_value in valid_media_types:
+            media_type_subtype = resource_dict.get('media_type').split('/')[1]
+            if media_type_subtype in valid_media_types:
                 g.add((
                     distribution,
                     DCAT.mediaType,
-                    URIRef(valid_media_types[lowercase_media_type_value])
+                    URIRef(valid_media_types[media_type_subtype])
                 ))
 
     def graph_from_catalog(self, catalog_dict, catalog_ref):