Merge pull request #441 from stan-dev/dependabot/github_actions/actions/checkout-6

Bump actions/checkout from 4 to 6

Author: florence-bockting

.github/workflows/test-coverage.yaml

@@ -18,7 +18,7 @@ jobs:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - uses: r-lib/actions/setup-r@v2
         with: