Update docker.io/library/postgres Docker tag to v13

docs/concepts-and-configurations/matrix-moderation.md

@@ -31,5 +31,5 @@ The bot is controlled and configured via a privileged *CCCHH Moderation Manageme
 There, individual actions can also be triggered through the bot as needed, such as redacting messages, kicking users from all or some channels, etc.
 
 It is also possible to make our moderation bot's local lists available to other entities and subscribe our bot to other entities' lists.
-Our list is published in `#general-moderation:hamburg.ccc.de` and can be made available to others upon request.
+Our list is published in `#general-moderation:hamburg.ccc.de` where other moderation bots can freely watch it.
 

resources/chaosknoten/lists/docker_compose/compose.yaml.j2

@@ -62,7 +62,7 @@ services:
       - POSTGRES_DB=mailmandb
       - POSTGRES_USER=mailman
       - "POSTGRES_PASSWORD={{ secret__lists__postgres_password }}"
-    image: docker.io/library/postgres:12-alpine
+    image: docker.io/library/postgres:13-alpine
     volumes:
       - /opt/mailman/database:/var/lib/postgresql/data
     networks: