Feed for all publications

[uxairibrar]

Closes #49

• Implemented GeoRSS feed for publications.
• Handled Point, Polygon, and GeometryCollection types.
• Fixed missing georss:point and georss:polygon in RSS output.
• Overrode add_item_elements() to ensure GeoRSS tags appear in XML.
• Added GeoRSS namespace (xmlns:georss) for standard compliance.
• Filtered publications with valid geometry and URLs to prevent errors.
• Tested and debugged feed output to confirm correct GeoRSS structure

[nuest]

Looks good!

To really judge if this is generating output as expected, please add a test case!

tests/test_publications_api.py should be a good starting point. The test should insert some test data (with different geometries) and then check if the created feed content is as expected. You can also store the generated XML in a file as a reference compare the two files, that is also pretty illustrating.