Updated mediawiki/extensions
Project: mediawiki/extensions/Echo  b392deda1dc75a6664f729bd64114dd44b9058d0

Delete invalid records from echo_target_page

Remove the records:

* If a page is no longer valid

* If a notification somehow has been read

* If a notification is no longer a bundle base and has not been removed

Change-Id: I282568691d6649c6e3263aea598c3bba29119a29