Windows CI started failing

[stephane-caron]

The build for 3da6629 that passed successfully now fails upon re-runs on all windows-py3* workflows. This is likely caused by an upstream dependency that started failing in an update. No failure reported in logs, only the absence of coverage data (although coverage runs successfully):

py37-windows: commands[7]> coverage report --include=\"qpsolvers/*\"
  No data to report.

• The issue started happening two days ago with this job, which is a minor change following a successful build.
• Previously this job worked fine. It installed coveralls-3.3.1, tox-4.0.16 and tox_gh_actions-2.12.0.

[stephane-caron]

• Identified a fix in Fix Windows CI issue related to tox #142
• Reported the issue to tox-gh-actions: No coverage report data on windows-latest workflows ymyzk/tox-gh-actions#140 It is actually a tox issue, see below.
• Report the issue to tox: No coverage report data on windows-latest workflows with tox >=4 tox-dev/tox#2778

[stephane-caron]

Fixed by #142