build(deps): bump actions/cache from 2 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v2...v4)

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

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

.github/workflows/staging-build.yaml

@@ -16,7 +16,7 @@ jobs:
  - name: set up docker buildx
  uses: docker/setup-buildx-action@v3
  - name: cache docker layers
- uses: actions/cache@v2
+ uses: actions/cache@v4
  with:
  path: /tmp/.buildx-cache
  key: ${{ runner.os }}-buildx-${{ github.sha }}