build(deps): bump Swatinem/rust-cache from 2.5.1 to 2.6.0

Bumps [Swatinem/rust-cache](https://github.com/swatinem/rust-cache) from 2.5.1 to 2.6.0.
- [Release notes](https://github.com/swatinem/rust-cache/releases)
- [Changelog](https://github.com/Swatinem/rust-cache/blob/master/CHANGELOG.md)
- [Commits](https://github.com/swatinem/rust-cache/compare/v2.5.1...v2.6.0)

---
updated-dependencies:
- dependency-name: Swatinem/rust-cache
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/docs.yaml

@@ -28,7 +28,7 @@ jobs:
           rustup default stable
 
       - name: Setup Rust cache
-        uses: Swatinem/rust-cache@v2.5.1
+        uses: Swatinem/rust-cache@v2.6.0
         with:
           save-if: "${{ github.event_name != 'pull_request' }}"