ci: use correct name for final stage

Dockerfile

@@ -61,7 +61,7 @@ RUN if [ "$MODEL_TYPE" = "sdxl" ]; then \
     fi
 
 # Stage 3: Final image
-FROM base
+FROM base as final
 
 # Copy models from stage 2 to the final image
 COPY --from=downloader /comfyui/models /comfyui/models