Bugfix: restore support for Color instances in Color.parse

[kajkal]

Restore support for already parsed Color instances as one of the valid Color.parse arguments as it is still required by some of the "functions".
Bug introduced in #94.

Launch Checklist

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!
• Briefly describe the changes in this PR.
• Link to related issues.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality.
• Document any changes to public APIs.
• Post benchmark scores.
• Add an entry to CHANGELOG.md under the ## main section.

[HarelM]

Thanks for making sure everything is as expected!

[kajkal]

Because of this bug, some render tests in PR #2376 do not pass.
I'm afraid that to fix this, a new release of maplibre-style-spec would be needed to allow the import of patched maplibre-style-spec in maplibre-gl-js :<

[HarelM]

I'll release one shortly.

[HarelM]

Can you please address the comment in the other PR before I release a new version so that for now there won't be a need to release another one for the small change?

[kajkal]

I addressed the comments, changes in maplibre-style-spec will not be required. You can proceed with the release of a new version of maplibre-style-spec.

[HarelM]

I've just released a new version.