Bump coursier/cache-action from 5 to 6

Bumps [coursier/cache-action](https://github.com/coursier/cache-action) from 5 to 6.
- [Release notes](https://github.com/coursier/cache-action/releases)
- [Commits](coursier/cache-action@v5...v6)

---
updated-dependencies:
- dependency-name: coursier/cache-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
           distribution: adopt
           java-version: ${{ matrix.java }}
       - name: Coursier cache
-        uses: coursier/cache-action@v5
+        uses: coursier/cache-action@v6
       - name: Build and test
         run: sbt scalafmtSbtCheck scalafmtCheck test:scalafmtCheck +test
       - run: rm -rf "$HOME/.ivy2/local" || true