fix: Don't run striptags on event descriptions that are emailed (ietf-tools#4267)

* fix: Don't run `striptags` on event descriptions that are emailed

Remove the `textify` filter, which is now unused.

Fixes ietf-tools#3600

* Update ietf_filters.py

* Update notification_email.txt

Author: larseggert

ietf/templates/community/notification_email.txt

@@ -8,7 +8,7 @@ Document: {{ event.doc }},
 
 Change by {{ event.by }} on {{ event.time }}:
 
-{{ event.desc|textify|striptags }}
+{{ event.desc|textify }}
 
 Best regards,