[Bug] Error Validating when Primary source type is other

[pjox]

When we tried to validate an entry for which the primary source type is other, for instance, Newspaper, we get the following error:

ValueError: 'Newspaper' is not in list
Traceback:
File "/home/yacine/.local/lib/python3.7/site-packages/streamlit/script_runner.py", line 354, in _run_script
    exec(code, module.__dict__)
File "/home/yacine/Code/data_sourcing/sourcing_sprint/app.py", line 380, in <module>
    main()
File "/home/yacine/Code/data_sourcing/sourcing_sprint/app.py", line 99, in main
    pages[app_mode](submission_info_dict)
File "/home/yacine/Code/data_sourcing/sourcing_sprint/app.py", line 305, in val_page
    form_source_category(entry_dict, app_categories, "val")
File "/home/yacine/Code/data_sourcing/sourcing_sprint/catalogue/catalogue_forms.py", line 909, in form_source_category
    if mode == "val"