[SDAChess]

Summary

Update all six Swatinem/rust-cache references to 6a7bc3ebce750e0a16a430dd57485acfdb38b05f, which includes the upstream fix that logs rustup toolchain-list failures at info level instead of warning (Swatinem/rust-cache#394).

Related Issue

No issue, as explicitly requested by the maintainer.

Changes

• Update the Rust and VM E2E setup actions, RPM workflow, and Windows MSVC workflow to the same commit.
• Remove the outdated v2.9.2 comments from the updated pins.

Release Notes

Testing

• Actionlint passes for both affected workflows (-shellcheck= -pyflakes=).
• YAML parsing passes for all four changed files using yq eval.
• git diff origin/main...HEAD --check passes.
• Reviewed the rebased diff and range-diff: only the six intended action-pin replacements remain; main's id: cache and cache-hit output wiring are preserved.
• Unit and E2E tests are not applicable to this action-pin update. GitHub Actions has not yet validated the rebased commit.

Checklist

• Follows Conventional Commits.
• Commit is signed off (DCO).
• Architecture documentation is not affected.