Bump julia-actions/install-juliaup from 2 to 3

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

---
updated-dependencies:
- dependency-name: julia-actions/install-juliaup
  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/CI.yml

@@ -28,7 +28,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       # Using `juliaup` over `setup-julia` so we can access beta versions easier
-      - uses: julia-actions/install-juliaup@v2
+      - uses: julia-actions/install-juliaup@v3
         with:
           channel: ${{ matrix.version }}
       - uses: julia-actions/cache@v3