chore: add Docker Buildx setup to workflow

- Integrated Docker Buildx setup step in docker-image-alpha.yml to enhance multi-platform build capabilities.

Author: Calcium-Ion

.github/workflows/docker-image-alpha.yml

@@ -38,6 +38,9 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Extract metadata (tags, labels) for Docker
         id: meta
         uses: docker/metadata-action@v5