CI: Bump actions/cache from 3 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 3 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v3...v4)

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

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

.github/workflows/reusable_build.yml

@@ -403,7 +403,7 @@ jobs:
       - name: Restore ccache cache
         id: restore-ccache-cache
         if: inputs.use_ccache_cache == true && steps.restore-ccache-cache-s3.outputs.cache-hit != 'true'
-        uses: actions/cache/restore@v3
+        uses: actions/cache/restore@v4
         with:
           path: openwrt/.ccache
           key: ${{ needs.setup_build.outputs.ccache_name }}-${{ hashFiles('openwrt/include/kernel-**') }}
@@ -688,7 +688,7 @@ jobs:
       - name: Save ccache cache
         if: inputs.use_ccache_cache == true && github.event_name == 'push' &&
           steps.restore-ccache-cache-s3.outputs.cache-hit != 'true'
-        uses: actions/cache/save@v3
+        uses: actions/cache/save@v4
         with:
           path: openwrt/.ccache
           key: ${{ steps.restore-ccache-cache.outputs.cache-primary-key }}