minimally require ipyparallel 6.2.5

[basnijholt]

Description

This means that we won't run into joblib/loky#240

This can be merged when ipyparallel 6.2.5 is on conda-forge.
On conda-forge now: conda-forge/ipyparallel-feedstock#48

Fixes #249.

Checklist

• Fixed style issues using pre-commit run --all (first install using pip install pre-commit)
• pytest passed

Type of change

Check relevant option(s).

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

[akhmerov]

Not sure it's appropriate: the problem is only there in python 3.8.

[basnijholt]

I think we really need this because whenever someone installed ipyparallel on Python 3.8, Adaptive's default scheduler (loky) is broken: joblib/loky#240.

I spoke with @jbweston and he also agreed.

[jbweston]

I think this is fine.

I would rather prioritize things "just working" on as wide a range of installs as possible, rather than requiring only the minimum version of everything.

[akhmerov]

Why do tests fail 🤔

[basnijholt]

Why do tests fail 🤔

@akhmerov, this is unrelated, the test is just flaky (which we should fix).