[ci] Bump actions/cache from 4 to 5

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 5.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v4...v5)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -40,7 +40,7 @@ jobs:
           ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Cache APT packages
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: /var/cache/apt/archives
           key: apt-${{ runner.os }}-${{ hashFiles('.github/workflows/ci.yml') }}