pin mineru[core]==3.4.0 in Dockerfile stage 9

与已验证的补丁B（适配3.4.0 predict_rec.py的ascontiguousarray写法）配套，
避免未来mineru升级破坏RDNA补丁。可复现构建。

Co-Authored-By: Claude <noreply@anthropic.com>

docker/Dockerfile

@@ -332,7 +332,7 @@ RUN set -ex && \
 # ===========================================================================
 RUN set -ex && \
     export http_proxy=${GIT_PROXY} https_proxy=${GIT_PROXY} && \
-    ${VENV}/bin/pip install 'mineru[core]' click gradio httpx cbor2 && \
+    ${VENV}/bin/pip install 'mineru[core]==3.4.0' click gradio httpx cbor2 && \
     ${VENV}/bin/python -c "import torch; from vllm.engine.arg_utils import AsyncEngineArgs; import mineru; import click; import gradio; import httpx; import cbor2; print('MinerU + Gradio + vllm deep + httpx + cbor2 imports OK')" && \
     ${VENV}/bin/mineru-gradio --help >/dev/null