Bump actions/cache from 5.0.5 to 6.1.0

Bumps [actions/cache](https://github.com/actions/cache) from 5.0.5 to 6.1.0.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@27d5ce7...55cc834)

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

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

Author: dependabot[bot]

.github/workflows/markdown.yml

@@ -18,7 +18,7 @@ jobs:
       with:
         persist-credentials: false
     - name: Restore lychee cache
-      uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
       with:
          path: .lycheecache
          key: cache-lychee-${{ github.sha }}