fix docs job

Author: NicolasHug

.github/workflows/docs.yaml

@@ -84,6 +84,7 @@ jobs:
           ${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