Bump actions/cache from 3 to 4 (#9646)

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](https://github.com/actions/cache/compare/v3...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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: brandon s allbery kf8nh <allbery.b@gmail.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

.github/workflows/bootstrap.yml

@@ -43,7 +43,7 @@ jobs:
           rm -rf ~/.config/cabal
           rm -rf ~/.cache/cabal
 
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         name: Cache the downloads
         id: bootstrap-cache
         with: