Update github-actions to v6

Author: renovate[bot]

.github/workflows/archiso.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
 
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3
@@ -27,7 +27,7 @@ jobs:
         password: ${{ secrets.GHCR_TOKEN }}
 
     - name: Build and push image
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       with:
         push: true
         context: .