chore(deps): bump actions/cache from 2 to 4 (#693)

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

Author: dependabot[bot]

.github/workflows/test.yml

@@ -116,7 +116,7 @@ jobs:
     # Doesn't cache PLTs based on mix.lock hash, as Dialyzer can incrementally update even old ones
     # Cache key based on Elixir & Erlang version.
     - name: Restore PLT cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: plt_cache
       with:
         key: |