Syntax error when running Pixelflut on Python 3.10

I tried to run Pixelflut on Ubuntu 22.04. Maybe the python version is too new? Which version should I use?

```
$ python3 --version && python3 pixelflut.py brain.py
Python 3.10.6

  File "pixelflut.py", line 22
    async = spawn
          ^
SyntaxError: invalid syntax
```