Update the testcases to use the new pmb v3 API.

Reflow the long string at the end manually

Use ruff instead of flake8. Aside from being substantially faster, ruff
includes a lot of flake's plug-ins built-in, some of which may be useful
to enable as a follow-up.

Put the argument at the right place.

Alpine 3.19 has the externally-managed-environment set, so this
flag is needed to let pip ruthlessly write to / of the container it
runs in. We could also use the flake8 package from alpine or use ruff,
but let's unblock it for now with this easy fix.

Seems to be necessary following some git CVE.

The args argument was removed to this function.

Fix for:
AttributeError: 'Namespace' object has no attribute 'logfd'

Import test_upstream_compat.py from pmaports.git, based on
test_upstream_compatibility.py and test_soname_bump.py with minor
adjustments. Make use of gitlab pages feature to publish a badge that we
can add to pmaports.git.

Currently, the test is failing because there are some compatibility
issues in pmaports that need to be addressed.