Bump julia-actions/cache from 1 to 2 (#60)

Bumps [julia-actions/cache](https://github.com/julia-actions/cache) from 1 to 2.
- [Release notes](https://github.com/julia-actions/cache/releases)
- [Changelog](https://github.com/julia-actions/cache/blob/main/devdocs/making_a_new_release.md)
- [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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/documentation.yml

@@ -20,7 +20,7 @@ jobs:
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1.9'
-      - uses: julia-actions/cache@v1
+      - uses: julia-actions/cache@v2
       - name: Install dependencies
         run: julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
       - name: Build and deploy