Don't require toml in [test] on Python 3.11+

[hroncok]

The test_toml_instead_of_tomli test is skipped on Python 3.11 anyway.

[layday]

I think we can just drop toml, it's been completely supplanted by tomli.

[hroncok]

If you wish to drop the fallback to toml, that also works for me.

[frenzymadness]

Now there is 'tomli >= 1.1.0; python_version < "3.11"' in dependencies, "toml >= 0.10.0" in test deps and "tomli" in typing deps.

[layday]

We have toml in test deps because we are testing against it. We have tomli in the typing deps because mypy simulates Python 3.7 and on 3.11, tomli is not required.

[hroncok]

Now there is 'tomli >= 1.1.0; python_version < "3.11"' in dependencies, "toml >= 0.10.0" in test deps and "tomli" in typing deps.

After this PR, the toml dependency is also conditional.

[henryiii]

I think we should drop toml, but this is a (small) step forward.

[layday]

I've got a PR to drop toml ready to go but I wanted to get #537 in first to avoid having to deal with merge conflicts. If you wanna get this in in the interim, we can do so, but I don't think there's much point unless we are gonna cut a release without toml as a test dependency.

[layday]

#567

[layday]

Merged #567.