ci: bump actions/cache

Bumps the github-actions group with 1 update in the /.github/actions/cache directory: [actions/cache](https://github.com/actions/cache).


Updates `actions/cache` from 5.0.4 to 6.1.0
- [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/v5.0.4...v6.1.0)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: 6.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
...

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

.github/actions/cache/action.yml

@@ -29,7 +29,7 @@ runs:
     # if it makes the expression below simpler. hashFiles() has a timer that
     # will fail the job if it times out, which can happen if there are too many
     # files to search through.
-    - uses: actions/cache@v5.0.4
+    - uses: actions/cache@v6.1.0
       with:
         path: .deps
         key: ${{ env.CACHE_KEY }}-${{ steps.image.outputs.version }}-${{ hashFiles('cmake**',