Bump julia-actions/cache from 1 to 2

Bumps [julia-actions/cache](https://github.com/julia-actions/cache) from 1 to 2.
- [Release notes](https://github.com/julia-actions/cache/releases)
- [Commits](julia-actions/cache@v1...v2)

---
updated-dependencies:
- dependency-name: julia-actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/Downgrade.yml

@@ -34,7 +34,7 @@ jobs:
       - uses: julia-actions/julia-downgrade-compat@v1
         with:
           skip: Pkg,TOML
-      - uses: julia-actions/cache@v1
+      - uses: julia-actions/cache@v2
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
       - uses: julia-actions/julia-buildpkg@v1