Support Unity 6+ Versioning and Add enableGpu Parameter

What's Changed

• Fix test workflows by @AndrewKahr in #632
• Add 'enableGpu' param, allowing running Unity w/o -nographics by @codenamesimon in #636
• Use capture group to find Unity version to support new 6000 versions by @AndrewKahr in #639

New Contributors

• @codenamesimon made their first contribution in #636

Full Changelog: v4...v4.2.2