Bump coursier/cache-action from 6 to 8

Bumps [coursier/cache-action](https://github.com/coursier/cache-action) from 6 to 8.
- [Release notes](https://github.com/coursier/cache-action/releases)
- [Commits](coursier/cache-action@v6...v8)

---
updated-dependencies:
- dependency-name: coursier/cache-action
  dependency-version: '8'
  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

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: coursier/cache-action@v6
+      - uses: coursier/cache-action@v8
       - uses: actions/setup-java@v4
         with:
           distribution: ${{ matrix.distribution }}
@@ -45,7 +45,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: coursier/cache-action@v6
+      - uses: coursier/cache-action@v8
       - uses: actions/setup-java@v4
         with:
           distribution: ${{ matrix.distribution }}