Update pretalx to new commit

pretalx/pretalx@11652a5...c819810

Author: martey

requirements/production.txt

@@ -14,7 +14,7 @@ easy-thumbnails==2.8.3
 gunicorn==20.1.0
 pinax-eventlog==5.1.1
 pip==22.3
--e git+https://github.com/pretalx/pretalx@11652a5857316b2280b16305621a0088d19adf12#egg=pretalx[redis]&subdirectory=src
+-e git+https://github.com/pretalx/pretalx@c81981092e01de5e7b4d8fadfab9c60cdc76de45#egg=pretalx[redis]&subdirectory=src
 psycopg2==2.9.4
 pytz==2022.5
 sentry-sdk==1.10.1