Bump coursier/cache-action from 6 to 7

Bumps [coursier/cache-action](https://github.com/coursier/cache-action) from 6 to 7.
- [Release notes](https://github.com/coursier/cache-action/releases)
- [Commits](coursier/cache-action@v6...v7)

---
updated-dependencies:
- dependency-name: coursier/cache-action
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/lts-backport.yaml

@@ -15,7 +15,7 @@ jobs:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0
-      - uses: coursier/cache-action@v6
+      - uses: coursier/cache-action@v7
       - uses: VirtusLab/[email protected]
       - run: scala-cli ./project/scripts/addToBackportingProject.scala -- ${{ github.sha }}
         env: