Update actions/checkout action to v5 (#47)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
       DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
       FORCE_COLOR: 1
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
     - name: Put back the git branch into git (Earthly uses it for tagging)
       run: |
         branch=""