Some nullable columns don't contain any `NULL` values

[di]

We have a number of columns that permit NULL values, but don't actually have any:

• file_events.additional
• file_events.ip_address_id
• journals.action
• journals.name
• oidc_publishers.discriminator
• organization_events.additional
• organization_events.ip_address_id
• organizations.is_approved
• pending_oidc_publishers.discriminator
• prohibited_user_names.prohibited_by
• project_events.additional
• project_events.ip_address_id
• projects.total_size
• release_dependencies.kind
• release_dependencies.specifier
• release_files.filename
• release_files.packagetype
• release_files.python_version
• release_files.size
• release_files.upload_time
• releases._pypi_ordering
• sponsors.service
• stripe_customers.billing_email
• stripe_subscription_items.subscription_item_id
• stripe_subscription_prices.price_id
• stripe_subscription_prices.tax_behavior
• stripe_subscription_products.product_id
• stripe_subscription_products.tax_code
• team_events.additional
• team_events.ip_address_id
• trove_classifiers.classifier
• trove_classifiers.ordering
• user_events.additional
• user_events.ip_address_id
• user_security_keys.public_key
• user_security_keys.sign_count
• vulnerabilities.aliases
• vulnerabilities.details
• vulnerabilities.fixed_in
• vulnerabilities.link

We should determine if any of these are actually required to permit NULL values, and migrate the rest to be non-nullable.

The above list was generated with:

DO $$ 
DECLARE 
    table_record record;
    col_name text;
    query int;
BEGIN
    FOR table_record IN (SELECT table_name FROM information_schema.tables WHERE table_schema = 'public') 
    LOOP
        FOR col_name IN 
            SELECT column_name 
            FROM information_schema.columns 
            WHERE table_name = table_record.table_name 
              AND is_nullable = 'YES'
        LOOP
            EXECUTE format('
                SELECT COUNT(*) 
                FROM %I 
                WHERE %I IS NULL', table_record.table_name, col_name) INTO query;
            
            IF query = 0 THEN
                RAISE NOTICE '%.%', table_record.table_name, col_name;
            END IF;
        END LOOP;
    END LOOP;
END $$;