Add notice on Python 3.9 to read me
@@ -30,7 +30,8 @@ of the [University of Passau](https://www.uni-passau.de).
## Prerequisites
Before you begin, ensure you have met the following requirements:
-- You have installed Python 3.8
+- You have installed Python 3.8 (we have not yet tested with Python 3.9, there might
+ be some problems due to changed internals regarding the byte-code instrumentation).
- You have a recent Linux/macOS/Windows machine.
## Installing Pynguin
