Release broken by older Python 3.7 package used by cibuildwheel.

[mjpieters]

The release build fails when building on MacOS and Windows for Python 3.7, because cibuildwheels uses the latest Python version that has a packager available for those platforms and the last packaged Python 3.7 release is 3.7.9.

That version lacks a security fix that our updated test suite relies on. See the release build log failures.

The same tests will also fail when run on older Python 3.8 and 3.9 releases. The versions affected are:

Python release	Patch versions affected
3.7	< 3.7.10
3.8	< 3.8.8
3.9	< 3.9.2

Describe the solution you'd like

We should mark the test as xfail if using such an old version of Python 3.7.

Describe alternatives you've considered

Drop support for Python 3.7. This would solve the release issue but anyone with an old Python 3.8 or 3.9 release might still get test failures.

Upgrading the cibuildwheel Python version is probably not an option, as 3.7.9 is the last packaged version of Python 3.7, meaning there are no MacOS and Windows packages for 3.7.10 and later that the project could use to install from.