Update pytorch_sphinx_theme2 (#3571)

Updated the PyTorch Sphinx theme version in requirements.

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@3066b6f62b0da01c52570c928281bca68287933d#egg=pytorch_sphinx_theme2
+-e git+https://github.com/pytorch/pytorch_sphinx_theme.git@f576ce406429f8ce11475ec096dda346df5b3b71#egg=pytorch_sphinx_theme2
 
 # Tutorial dependencies
 tqdm==4.66.1