Bump actions/cache from 2 to 4 (#13)

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

.github/workflows/CI.yml

@@ -76,7 +76,7 @@ jobs:
         with:
           version: ${{ steps.version_resolver.outputs.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
             path: ~/.julia/artifacts
             key: ${{ runner.os }}-test-artifacts-${{ hashFiles('**/Project.toml') }}