Tests still install legacy Python bindings

[link2xt]

relay/cmdeploy/src/cmdeploy/cmdeploy.py

Lines 209 to 211 in fa5a6a6

	x = importlib.util.find_spec("deltachat")
	if x is None:
	out.check_call(f"{sys.executable} -m pip install deltachat")

These bindings don't work on macOS:
https://support.delta.chat/t/cant-launch-scripts-cmdeploy-test-on-mac/4356

Are they even needed? We have dependencies in pyproject.toml, there should be no need to call pip install manually.

[link2xt]

Previous related issue:
#501

Legacy bindings are still used here:

relay/cmdeploy/src/cmdeploy/tests/plugin.py

Lines 300 to 303 in fa5a6a6

	def cmfactory(request, gencreds, tmpdir, maildomain):
	# cloned from deltachat.testplugin.amfactory
	pytest.importorskip("deltachat")
	from deltachat.testplugin import ACFactory