Update pytorch_sphinx_theme2 to version 0.4.9

Author: svekars

.ci/docker/requirements.txt

@@ -16,7 +16,7 @@ pandocfilters==1.5.1
 markdown==3.8.2
 
 # PyTorch Theme
-pytorch_sphinx_theme2==0.4.6
+pytorch_sphinx_theme2==0.4.9
 
 # Tutorial dependencies
 tqdm==4.66.1