chore: Add a CI job to run tests in Conda, to detect dependency failure earlier

[jstlaurent]

Changelogs

• Add a GitHub Actions job to run the test suite under a Conda environment
• Update the dependency list by removing unused ones

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Checklist:

• Was this PR discussed in an issue? It is recommended to first discuss a new feature into a GitHub issue before opening a PR.
• Add tests to cover the fixed bug(s) or the newly introduced feature(s) (if appropriate).
• Update the API documentation if a new function is added, or an existing one is deleted.
• Write concise and explanatory changelogs above.
• If possible, assign one of the following labels to the PR: feature, fix, chore, documentation or test (or ask a maintainer to do it for you).

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Since we've been tripped by some dependendencies that don't have all platforms supported in Conda, adding a CI flow that will run the tests from a clean Conda environment should raise these issues earlier.

[cwognum]

Thanks! 🙏

Random thought: As the CICD continues to grow, is there value in changing to a different service (e.g. I think I've seen @Andrewq11 use CodeFresh). I have never actually worked with such services, so I'm not sure it's worth it.

[Andrewq11]

This is awesome, thanks @jstlaurent.

It would've been nice to do this test on conda-forge's CI infrastructure. That was the original thought, but apparently we cannot reliably get access to non-Linux runners for testing there.

No issue though, this will be great for avoiding any further upstream dependency hiccups 🚀

[mercuryseries]

Thanks, @jstlaurent!