Support for Swift 6.0?

Hello, The `project_precommit_check` script mentioned in the [pull request template](https://github.com/swiftlang/swift-source-compat-suite/blob/main/.github/PULL_REQUEST_TEMPLATE.md) is limited to Swift up to 5.10. As a consequence, one can't submit a pull request that targets Swift 6.0, and pass pull request requirements.