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] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci-ubuntu.yml

@@ -74,7 +74,7 @@ jobs:
       # This caching step allows us to save a lot of building time by
       # saving the previous build.
       - name: Restore cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v5
         id: cache
         with:
           path: |
@@ -119,7 +119,7 @@ jobs:
       # This caching step allows us to save a lot of building time by
       # saving the previous build.
       - name: Save cache
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v5
         if: always()
         with:
           path: |