Update Dockerfile.ci to replace 'uv pip' with 'pip' for 'pplx_kernels' installation, ensuring consistency in package management across the CI environment.

Signed-off-by: tzhouam <tzhouam@connect.ust.hk>

docker/Dockerfile.ci

@@ -26,7 +26,7 @@ RUN uv pip uninstall --system nvidia-cublas-cu12
 # Use bash -c so that $(python3 -c ...) is expanded inside the container.
 RUN uv pip install --system --no-cache-dir ".[dev]"
 
-RUN uv pip install --system --upgrade --force-reinstall "pplx_kernels"
+RUN pip install --upgrade --force-reinstall "pplx_kernels"
 
 RUN /bin/bash -c 'FLASHINFER_CUDA_TAG="$(python3 -c "import torch; print((torch.version.cuda or \"12.4\").replace(\".\", \"\"))")" && \
     uv pip install --system --upgrade --force-reinstall \