deps(actions): bump actions/cache in the github-actions group (llm-d#788)

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


Updates `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
  dependency-group: github-actions
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci-pr-checks.yaml

@@ -46,7 +46,7 @@ jobs:
           echo "build=$(docker volume inspect llm-d-gobuildcache -f '{{.Mountpoint}}')" >> $GITHUB_OUTPUT
 
       - name: Cache Go modules and build cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: |
             ${{ steps.go-cache.outputs.mod }}
@@ -67,7 +67,7 @@ jobs:
       # compare-coverage.sh reports all components as "new" and exits 0.
       - name: Restore main branch coverage baseline
         if: github.event_name == 'pull_request'
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v5
         with:
           path: coverage/baseline
           key: coverage-main
@@ -93,7 +93,7 @@ jobs:
 
       - name: Save coverage baseline (main branch only)
         if: github.ref == 'refs/heads/main' && github.event_name == 'push'
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v5
         with:
           path: coverage/baseline
           key: coverage-main