Bump julia-actions/setup-julia from 2.0.0 to 2.3.0 (#760)

Bumps [julia-actions/setup-julia](https://github.com/julia-actions/setup-julia) from 2.0.0 to 2.3.0.
- [Release notes](https://github.com/julia-actions/setup-julia/releases)
- [Changelog](https://github.com/julia-actions/setup-julia/blob/master/devdocs/making_a_new_release.md)
- [Commits](julia-actions/setup-julia@f225878...780022b)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/exercise-tests.yml

@@ -31,7 +31,7 @@ jobs:
     steps:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
 
-      - uses: julia-actions/setup-julia@f2258781c657ad9b4b88072c5eeaf9ec8c370874
+      - uses: julia-actions/setup-julia@780022b48dfc0c2c6b94cfee6a9284850107d037
         with:
           version: ${{ matrix.julia-version }}