minor installation/test running fixing

[alessandrofelder]

Description

What is this PR

• [x] Bug fix
• [ ] Addition of a new feature
• [ ] Other

Why is this PR needed?

• I managed to remove a pyside2 dev dependency in the mega-fix branch, which was needed
• we should stop supporting py3.8 and test on py3.11 to follow NEP 29
• CI currently fails fast, so it's hard to get an overview of how tests are faring across OSs and Python version

What does this PR do?

• adds pyside2 to dependencies
• drops support for Python 3.8.
• ensures all CI workflows are run even if one fails by setting strategy.fail-fast = false

References

Closes #252 Closes #256

How has this PR been tested?

Tests fail due to other reasons that lack of Qt back in CI run

Is this a breaking change?

Nope

Does this PR require an update to the documentation?

Not really, but see https://github.com/brainglobe/brainrender/issues/253 for docs changes/improvements needed as part of megafix

Checklist:

• [n/a] The code has been tested locally
• [n/a] Tests have been added to cover all new functionality (unit & integration)
• [n/a] The documentation has been updated to reflect any changes
• [x] The code has been formatted with pre-commit