mopidy: add setuptools to fix 'No module named pkg_resources'

Python 3.12 slim doesn't bundle setuptools. mopidy imports pkg_resources
from setuptools; without it, mopidy crashes on startup.

infra/mopidy/Dockerfile

@@ -16,6 +16,7 @@ RUN apt-get update \
  && rm -rf /var/lib/apt/lists/*
 
 RUN pip install --no-cache-dir \
+    setuptools \
     Mopidy==3.4.2 \
     Mopidy-Qobuz \
     Mopidy-Local