Bump freckle/stack-action from 4 to 5

Bumps [freckle/stack-action](https://github.com/freckle/stack-action) from 4 to 5.
- [Commits](freckle/stack-action@v4.0.0...v5)

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

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

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - id: generate
-        uses: freckle/stack-action/generate-matrix@v4
+        uses: freckle/stack-action/generate-matrix@v5
     outputs:
       stack-yamls: ${{ steps.generate.outputs.stack-yamls }}