py-matplotlib version conflict

There is a conflict (actually 2 conflicts) with the matplotlib versions in our current environment:

• wf-brainscales2-demos needs py-matplotlib@3.5.2:
• py-netpyne needs py-matplotlib@:3.5.1

@vbragin is the matplotlib issue maybe fixed by now? @emuller could a (slightly) older version work?

At the same time,

• py-matplotlib@3.5 needs py-setuptools-scm@4:6
• py-quantities needs py-setuptools-scm@7: (builds, but import quantities throws an error)

That part is probably fixable, either by skipping the upper limit on the matplotlib spack package or by using a wheel for quantities.