Update seminar.md

seminar.md

@@ -50,6 +50,9 @@ and a mattermost channel for chat. To join the mattermost channel:
 
 |Date|Speaker|Title/Topic|
 |----|-------|-----------|
+|2021-09-27| - | |
+|2021-08-30| - | *summer break* |
+|2021-08-02| - | *summer break* |
 |2021-07-05| - | *summer break* |
 |2021-06-07| - | *summer break* |
 |2021-05-10| Anton Lorenzen | A type system for natural language ([slides](https://nc.kwarc.info/s/piPmS9rzJar2bkB)) |