Add TSC mailing list topic to agenda (#1327)

Author: benjie

agendas/2023/07-Jul/06-wg-primary.md

@@ -128,5 +128,6 @@ hold additional secondary meetings later in the month.
    - [Ready for review](https://github.com/graphql/graphql-wg/issues?q=is%3Aissue+is%3Aopen+label%3A%22Ready+for+review+%F0%9F%99%8C%22+sort%3Aupdated-desc)
    - [All open action items (by last update)](https://github.com/graphql/graphql-wg/issues?q=is%3Aissue+is%3Aopen+label%3A%22Action+item+%3Aclapper%3A%22+sort%3Aupdated-desc)
    - [All open action items (by meeting)](https://github.com/graphql/graphql-wg/projects?query=is%3Aopen+sort%3Aname-asc)
+1. TSC: update on the TSC mailing list (3m, Benjie)
 1. Defer execution model - Early vs Delayed (30m, Rob)
    - [Discussion](https://github.com/robrichard/defer-stream-wg/discussions/68)