Merge pull request from GHSA-9928-3cp5-93fm

* Fix attachments getting processed despite failing content-type validation

* Add a restrictive ImageMagick security policy tailored for Mastodon

* Fix misdetection of MP3 files with large cover art

* Reject unprocessable audio/video files instead of keeping them unchanged

app/models/concerns/attachmentable.rb

@@ -22,15 +22,14 @@ module Attachmentable
 
   included do
     def self.has_attached_file(name, options = {}) # rubocop:disable Naming/PredicateName
-      options = { validate_media_type: false }.merge(options)
       super(name, options)
-      send(:"before_#{name}_post_process") do
+
+      send(:"before_#{name}_validate") do
         attachment = send(name)
         check_image_dimension(attachment)
         set_file_content_type(attachment)
         obfuscate_file_name(attachment)
         set_file_extension(attachment)
-        Paperclip::Validators::MediaTypeSpoofDetectionValidator.new(attributes: [name]).validate(self)
       end
     end
   end