Setting FFmpeg version to 6

Author: scotts

.github/workflows/benchmarks.yaml

@@ -32,7 +32,7 @@ jobs:
         run: python -m pip install --upgrade pip
       - name: Install dependencies and FFmpeg
         run: |
-          conda install ffmpeg pkg-config -c conda-forge
+          conda install "ffmpeg=6" pkg-config -c conda-forge
           python -m pip install --pre torch torchvision torchaudio --index-url https://download.pytorch.org/whl/nightly/cpu
           python -m pip install decord matplotlib pandas numpy
           ffmpeg -version