Fix spdlog error with sed in GitHub actions

[izzy2lost]

Add sed commands to GitHub Actions workflows to resolve spdlog compilation errors in torch/CMakeLists.txt.

The torch/CMakeLists.txt was failing to find spdlog as a required package, leading to build failures. This PR modifies the build process to first attempt a quiet find_package for spdlog, and if not found, it fetches spdlog via FetchContent. It also adds conditional linking to correctly handle spdlog::spdlog or spdlog targets, improving build robustness.

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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[gemini-code-assist]

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