Bump actions/cache from 3 to 4

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>

.github/workflows/test.yml

@@ -16,13 +16,13 @@ jobs:
    runs-on: ubuntu-20.04
    steps:
      - uses: actions/checkout@v4
-     - uses: actions/cache@v3
+     - uses: actions/cache@v4
        with:
          path: deps
          key: ${{ runner.os }}-mix-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
          restore-keys: |
            ${{ runner.os }}-mix-
-     - uses: actions/cache@v3
+     - uses: actions/cache@v4
        with:
          path: _build
          key: build-elixir-${{ matrix.elixir }}-otp-${{ matrix.otp }}-mix-${{ hashFiles('mix.lock') }}