Bump julia-actions/cache from 2 to 3

Bumps [julia-actions/cache](https://github.com/julia-actions/cache) from 2 to 3.
- [Release notes](https://github.com/julia-actions/cache/releases)
- [Commits](julia-actions/cache@v2...v3)

---
updated-dependencies:
- dependency-name: julia-actions/cache
  dependency-version: '3'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/downgrade.yml

@@ -24,6 +24,6 @@ jobs:
       - uses: julia-actions/julia-downgrade-compat@v2
         with:
           skip: Pkg,TOML,InteractiveUtils,Random,LinearAlgebra
-      - uses: julia-actions/cache@v2
+      - uses: julia-actions/cache@v3
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1