Fix: DistributionWorkerでString to Integerのエラーが出る問題 (#344)

* Fix: DeliveryWorkerでString to Integerのエラーが出る問題

* Test: Mastodon v3向け

app/models/instance_info.rb

@@ -40,6 +40,7 @@ class InstanceInfo < ApplicationRecord
     return false if info.nil?
 
     return true if EMOJI_REACTION_AVAILABLE_SOFTWARES.include?(info['software'])
+    return false if info.data['metadata'].nil? || !info.data['metadata'].is_a?(Hash)
 
     features = info.data.dig('metadata', 'features')
     return false if features.nil? || !features.is_a?(Array)