CI: Add py310 to integration test matrix

[VeckoTheGecko]

In #1769 (review) there was some py310 incompatible code. Adding py310 to integration test matrix so that it fails in CI in future.

[VeckoTheGecko]

Sidenote: @erikvansebille Is the purpose of the integration tests to make sure that the tutorials are working correctly, or to actually test the codebase? If the former, how do you feel about removing windows and mac from the integration tests? (as windows/mac incompatibility should arise in the unit tests)

Has Windows integration tests failed by themselves before?

If we're unsure perhaps we should lean towards keeping

[erikvansebille]

Has Windows integration tests failed by themselves before?

Yes, if I remember well this has happened on the docs/examples/example_dask_chunk_OCMs.py test before; but these are rather flaky anyways (they also failed recently with a new array version in #1762). So I think these integration tests are more for external dependency deprecations than our own code-development

If we're unsure perhaps we should lean towards keeping

We could perhaps run the windows and macOS integration tests only every month or so. That will reduce our CI-burden (and save some energy).

[VeckoTheGecko]

if I remember well this has happened on the docs/examples/example_dask_chunk_OCMs.py

I see. I thought that integration tests were just the notebooks.

[erikvansebille]

I see. I thought that integration tests were just the notebooks.

No, the notebooks (but only those that don't start with documentation_) and the docs/examples/*.py files

[VeckoTheGecko]

Yes. Though technically the __main__ parts of the docs/examples/example*.py scripts are unit tests since test_example_script() is in tests/test_examples.py.

What has been the rule of thumb for whether something is a unit or integration test?

[erikvansebille]

What has been the rule of thumb for whether something is a unit or integration test?

The integration tests use 'real-world' hydrodynamic datasets (GlobCurrent, MITgcm, OFAM, ...) and/or are full-fledged example simulations (e.g. Peninsula, Stommel, Brownian).