chore(deps): bump actions/cache from 3 to 4 (#126)

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

.github/workflows/fastly-edge-assignments.yml

@@ -22,7 +22,7 @@ jobs:
           submodules: true
 
       # Cache Rust toolchain and dependencies
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/bin/