🧹 Remove unused Dist import in TestableMod

[sayore]

🎯 What: Removed unused import net.neoforged.api.distmarker.Dist from TestableMod.java.
💡 Why: The import was not referenced anywhere in the file, so removing it improves code readability and health.
✅ Verification: Verified by building the codebase (gradle build) to ensure no functionality is broken, and no new compilation errors arise. Code review confirmed this is safe.
✨ Result: A cleaner file structure.

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PR created automatically by Jules for task 4598050511483448410 started by @sayore

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