Show reviewer roulette when there's only codeowners approvals

Signed-off-by: Rémy Coutable <remy@rymai.me>

danger/roulette/Dangerfile

@@ -97,7 +97,7 @@ categories = roulette.prepare_categories(changes.keys - [:unknown])
 # Skip specialty reviews for stable branch MRs since they have already been merged to the default branch
 categories.subtract([:database, :ux, :analytics_instrumentation]) if stable_branch.valid_stable_branch?
 
-if changes.any?
+if changes.any? || roulette.required_approvals.any?
   random_roulette_spins = roulette.spin(nil, categories)
 
   rows = random_roulette_spins.map do |spin|