Bump actions/cache from 2 to 4

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]>

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
           version: ${{ matrix.julia-version }}
           arch: ${{ matrix.julia-arch }}
       - name: Cache artifacts
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         env:
           cache-name: cache-artifacts
         with:
@@ -57,7 +57,7 @@ jobs:
         with:
           version: "^1.7.0-0"
       - name: Cache artifacts
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         env:
           cache-name: cache-artifacts
         with: