update to artifact v4

Author: Robert Schuh

.github/workflows/docker-publish.yml

@@ -63,7 +63,7 @@ jobs:
       - name: Upload digest
         uses: actions/upload-artifact@v4
         with:
-          name: digests-${{ matrix.runs-on }}
+          name: digests-${{ matrix.platform }}
           path: /tmp/digests/*
           if-no-files-found: error
           retention-days: 1
@@ -80,7 +80,7 @@ jobs:
         uses: actions/download-artifact@v4
         with:
           path: /tmp/digests
-          pattern: digests-${{ matrix.runs-on }}
+          pattern: digests-${{ matrix.platform }}
           merge-multiple: 'true'
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3