Update PyTorch Sphinx theme to a newer commit

Author: svekars

.ci/docker/requirements.txt

@@ -16,7 +16,7 @@ pandocfilters==1.5.1
 markdown==3.8.2
 
 # PyTorch Theme
--e git+https://github.com/pytorch/pytorch_sphinx_theme.git@c2e38b37f3c432c610639f06d1d421c6df4c225c#egg=pytorch_sphinx_theme2
+-e git+https://github.com/pytorch/pytorch_sphinx_theme.git@71e55749be14ceb56e7f8211a9fb649866b87ad4#egg=pytorch_sphinx_theme2
 
 # Tutorial dependencies
 tqdm==4.66.1