Change PyTorch Sphinx theme to GitHub source

Updated the PyTorch Sphinx theme dependency to a GitHub source.

Author: svekars

.ci/docker/requirements.txt

@@ -16,7 +16,9 @@ pandocfilters==1.5.1
 markdown==3.8.2
 
 # PyTorch Theme
-pytorch_sphinx_theme2==0.4.2
+# pytorch_sphinx_theme2==0.4.2
+
+git+https://github.com/pytorch/[email protected]
 
 # Tutorial dependencies
 tqdm==4.66.1