ci(deps): bump actions/checkout from 5 to 6 (#228)

Author: dependabot[bot]

.github/workflows/publish.yml

@@ -18,7 +18,7 @@ jobs:
       major: ${{ steps.tags.outputs.major }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Extract version number
         id: tags

.github/workflows/self-test.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Build container
         run: |