Bump actions/download-artifact from 2 to 4.1.7 in /.github/workflows

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 2 to 4.1.7.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v2...v4.1.7)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/ci.yml

@@ -99,7 +99,7 @@ jobs:
           key: ${{ runner.os }}-sbt-cache-v2-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}
 
       - name: Download target directories (2.12.14)
-        uses: actions/download-artifact@v2
+        uses: actions/download-artifact@v4.1.7
         with:
           name: target-${{ matrix.os }}-2.12.14-${{ matrix.java }}