Change algorithm of follow recommendations (#28314)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

app/models/follow_request.rb

@@ -45,10 +45,15 @@ class FollowRequest < ApplicationRecord
   end
 
   before_validation :set_uri, only: :create
+  after_commit :invalidate_follow_recommendations_cache
 
   private
 
   def set_uri
     self.uri = ActivityPub::TagManager.instance.generate_uri_for(self) if uri.nil?
   end
+
+  def invalidate_follow_recommendations_cache
+    Rails.cache.delete("follow_recommendations/#{account_id}")
+  end
 end