Fix workflow pyenv matrix Python 3.9 and 3.11

There's no 3.9.3, only 3.9.2, which is also the correct Debian version.

3.11.1 is available in pyenv 2.3.8, but 2.3.7 is currently in use by the
  Github action. So 3.11 is used, which uses the latest patch version

.github/workflows/run_tests.yml

@@ -15,8 +15,8 @@ jobs:
         python:
           - "3.5.3"  # Debian Stretch
           - "3.7.3"  # Debian Buster
-          - "3.9.3"  # Debian Bullseye
-          - "3.11.1" # Debian Bookworm
+          - "3.9.2"  # Debian Bullseye
+          - "3.11"   # Debian Bookworm uses 3.11.1, but it's in a newer pyenv release
     steps:
       - uses: actions/checkout@v3