Fix build with Docker Desktop on Windows

[MuellerKlaus]

Automatic line conversion makes sha256sum fail if build on Windows

💸 TL;DR

sha256sum fails to run if project checked out from Windows with automatic line ending conversion. The change mark the 'checksums.txt' file as non-text.

📜 Details

N/A

🧪 Testing Steps / Validation

• checkout repo on Windows system with git
• try to run 'docker build --progress plain .'
• build fails with 'sha256sum: checksums.txt: no file was verified'
• build succeed after set git attributes

✅ Checks

• CI tests (if present) are passing
• Adheres to code style for repo
• Contributor License Agreement (CLA) completed if not a Reddit employee