build(deps): bump actions/cache from 4 to 6 (#918)

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 6.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](https://github.com/actions/cache/compare/v4...v6)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/rust.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
       - name: Cache Cargo registry
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cargo/registry