Unpin dask following dask 2021.8.1

[ericpre]

Description of the change

• Unpin dask, since the fix for Regression: poor memory management in threads and sync schedulers dask/dask#7583 have been released in 2021.8.1.
• Tidy up install_requires in setup.py
• Specify numba version in oldest supported version build

Progress of the PR

• [N/A] Docstrings for all functions
• [N/A] Unit tests with pytest for all lines
• [N/A] Clean code style by running black via pre-commit

For reviewers

• The PR title is short, concise, and will make sense 1 year later.
• New functions are imported in corresponding __init__.py.
• New features, API changes, and deprecations are mentioned in the unreleased
  section in doc/changelog.rst.
• New contributors are added to .all-contributorsrc and the table is regenerated.

[hakonanes]

Thank you, @ericpre!

Is it OK if I update this PR with these changes:

1. Add you to the All Contributors table with code and maintenance badges?
2. Add a changelog entry and add your name "Eric Prestat" to the package credits in release.py?

[hakonanes]

This PR will close #359.

[ericpre]

Yes, sure!

[hakonanes]

I would appreciate it if you could change the base branch back to develop. After v0.5, these changes would go to main and we would immediately release a patch.

[hakonanes]

I would appreciate it if you could change the base branch back to develop. After v0.5, these changes would go to main and we would immediately release a patch.

So the guidelines in the contributing guide is wrong until v0.5. I'm sorry for the confusion.

[ericpre]

Done.

[ericpre]

Does it mean the next release will be done once the 0.5 milestone is completed?

[hakonanes]

Does it mean the next release will be done once the 0.5 milestone is completed?

Good point. With the EBSD orientation refinement functionality implemented in #387, the improvements to simulated pattern dictionary generation in #405, and the upcoming improvements in #419 (plan to finish within the weekend), I think we should release v0.5 with these changes. So hopefully within the weekend or early next week. I'll update the milestone now, thanks for pointing that out.