Add Support for Algolia V4 - Breaking Change

[TheoGibbons]

This pull request updates the Laravel Scout package to support Algolia V4. This update addresses the lack of compatibility with Algolia V4, as discussed in Issue #855.

Key Changes:

• Added support for Algolia V4.
• Removed support for Algolia V3, making this a breaking change.
• Removed support for PHP 8.0 as Algolia V4 requires php 8.1

This guide helped with the upgrade: Algolia V4 Upgrade Guide.

Please review the following:

1. I'll leave it up to you whether this should be merged, considering the breaking change that removes Algolia V3 compatibility and introduces a PHP 8.1 requirement.
2. I'm not sure why the Meilisearch checks are failing, as this update shouldn't have affected them. It looks like they are just timing out 🤷
3. I've had this running in production for two days without issue.

[taylorotwell]

The upgrade guide would need to be updated.

[driesvints]

@TheoGibbons can you send this to 11.x instead?