Slugify platform name for digest upload

.github/workflows/ci.yml

@@ -72,10 +72,14 @@ jobs:
           digest="${{ steps.build.outputs.digest }}"
           touch "/tmp/digests/${digest#sha256:}"
 
+      - name: Platform slug
+        id: platform-slug
+        run: echo "platform=${{ matrix.platform }}" | tr '/' '-' >> $GITHUB_OUTPUT
+
       - name: Upload digest
         uses: actions/upload-artifact@v4
         with:
-          name: digests
+          name: digests-${{ steps.platform-slug.outputs.platform }}
           path: /tmp/digests/*
           if-no-files-found: error
           retention-days: 1
@@ -88,8 +92,9 @@ jobs:
       - name: Download digests
         uses: actions/download-artifact@v4
         with:
-          name: digests
           path: /tmp/digests
+          pattern: digests-*
+          merge-multiple: true
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3