Set LD_LIBRARY_PATH for linux_cuda_wheel workflow (#1034)

Author: atalman

.github/workflows/linux_cuda_wheel.yaml

@@ -95,12 +95,13 @@ jobs:
           # We install conda packages at the start because otherwise conda may have conflicts with dependencies.
           # Note: xorg-libxau was addded to fix a problem with ffmpeg 4. We should consider removing it.
           default-packages: "nvidia/label/cuda-${{ matrix.cuda-version }}.0::libnpp nvidia::cuda-nvrtc=${{ matrix.cuda-version }} nvidia::cuda-toolkit=${{ matrix.cuda-version }} nvidia::cuda-cudart=${{ matrix.cuda-version }} nvidia::cuda-driver-dev=${{ matrix.cuda-version }} conda-forge::ffmpeg=${{ matrix.ffmpeg-version-for-tests }} conda-forge::xorg-libxau"
-      - name: Check env
+      - name: Check env, set LD_LIBRARY_PATH
         run: |
           ${CONDA_RUN} env
           ${CONDA_RUN} conda info
           ${CONDA_RUN} nvidia-smi
           ${CONDA_RUN} conda list
+          echo LD_LIBRARY_PATH=$CONDA_PREFIX/lib:/usr/local/cuda/lib64/:${LD_LIBRARY_PATH} >> $GITHUB_ENV
       - name: Assert ffmpeg exists
         run: |
           ${CONDA_RUN} ffmpeg -buildconf