Sourcery crashes with swiftLanguageVersions: [.v6] or swiftLanguageMode: [.v6] in a Swift Package

[iDylanK]

Description:

Sourcery crashes (fatalError) when the following configuration is used in a Swift Package's Package.swift file:

swiftLanguageVersions: [.v6],
swiftLanguageMode: [.v6]

Steps to Reproduce

Create a Swift Package and set swiftLanguageVersions and swiftLanguageMode to .v6 in Package.swift.
Run Sourcery against the package.
Observe the crash.

Expected Behavior

Sourcery should handle Swift 6 language versions and modes without crashing.

Actual Behavior

Sourcery crashes immediately when analyzing the Swift package.

Environment

Sourcery version: [Specify version]
Swift version: 6.0 (or development snapshot)
Operating System: [macOS version]
Additional Context
[Include any relevant logs, crash reports, or configurations.]