Upgrade css-selector-parser

`css-selector-parser` v3 is a breaking change in their API. Unfortunately we add the parser to the `imports` object of axe, meaning we can't upgrade to the latest without also creating a breaking change. We looked at creating a backwards compatible wrapper for the latest changes, but it was too much work and didn't work out to be 1:1.

We should upgrade to the latest non-breaking change version, then figure out how to handle the breaking change for v5. Either we remove the `imports` object from axe-core or just upgrade with a breaking change.

Ref: https://github.com/dequelabs/axe-core/pull/4264