Depend on tagged release of swift-syntax to enable Xcode 26 pre-built compilation cache

### New Issue Checklist - [x] I've Updated SwiftLint to the latest version. - [x] I've searched for [existing GitHub issues](https://github.com/realm/SwiftLint/issues). ### Feature or Enhancement Proposal Starting with Xcode 26, Apple provides **pre-built swift-syntax binaries** that are bundled with Xcode. This allows projects to skip compiling swift-syntax from source during clean builds, saving significant build time (minutes in some cases). However, this optimization **only applies when packages depend on a tagged release** of swift-syntax (e.g., `601.0.1`). SwiftLint currently depends on a prerelease version (`604.0.0-prerelease-2026-03-31`), which means: 1. Xcode cannot use its pre-built swift-syntax and must compile it from source on every clean build. 2. Any downstream package that also depends on swift-syntax is forced to match the same prerelease version, preventing them from benefiting from the pre-built cache as well. It would be great if SwiftLint could depend on a tagged (stable) release of swift-syntax so that: - Clean build times are reduced for all projects using SwiftLint as a build tool plugin. - Downstream packages are no longer forced into prerelease swift-syntax versions.