Handle flaky unit tests

[gferragu]

We know that gmprocess has a couple of flaky unit tests that can fail in CI runners on both Gitlab and Azure due to dependence on runner state and/or tests running in parallel.

We should not indicate total failure for this case. For now, this flexibility can be added with the --maxfail=N argument via pytest

A better solution is to use a fixture to mark specific tests as flaky and use this, or the Azure project settings, to re-run some tests and check if the continually fail