Find or create demo categories for joatu demo data

Author: rsmithlal

app/builders/better_together/joatu_demo_builder.rb

@@ -257,7 +257,7 @@ def build_agreements(requests:, offers:) # rubocop:todo Metrics/AbcSize, Metrics
       # -- Helpers --
 
       def find_category(name)
-        ::BetterTogether::Joatu::Category.i18n.find_by(name: name)
+        ::BetterTogether::Joatu::Category.i18n.find_or_create_by(name: name)
       end
 
       def identifier_for(name)