fix SyncDestroy action policy to be run on before_destroy

Author: ruggi

lib/stream_rails/sync_policies.rb

@@ -28,8 +28,8 @@ def add_to_feed
 
     module SyncDestroy
       def self.included(base)
-        if base.respond_to? :after_commit
-          base.after_commit :remove_from_feed, on: :destroy
+        if base.respond_to? :before_destroy
+          base.before_destroy :remove_from_feed
         elsif Object.const_defined?('Sequel') && base < Sequel::Model
           base.instance_eval do
             define_method(:before_destroy) do |*args|