Windows linter tests are failing even though GitHub Actions shows they are passing

As per the output of this GitHub Actions run, tox's output shows that the "lint" testenv is presently failing, however, GitHub Actions indicates that all tests are passing. This is a problem: if tests are failing according to tox, then they should fail according to GHA also, otherwise GHA becomes rather useless.

This discrepancy should be investigated and fixed such that a failed tox test run registers properly as a failure on GHA.