ci: Fix failures in vs2019 jobs on Azure
pip warns about being out of date and powershell interprets that as an
error because reasons.
Found in
@@ -155,7 +155,7 @@ steps:
python --version
# Needed for running unit tests in parallel.
- python -m pip install --upgrade pytest-xdist
+ python -m pip --disable-pip-version-check install --upgrade pytest-xdist
echo ""
