Fixed jinja2 environment autoescape to enable select extensions (#3635)

Co-authored-by: Nicolas Hug <nicolashug@fb.com>

.circleci/regenerate.py

@@ -15,6 +15,7 @@ https://github.com/pytorch/vision/pull/1321#issuecomment-531033978
 """
 
 import jinja2
+from jinja2 import select_autoescape
 import yaml
 import os.path
 
@@ -295,7 +296,7 @@ if __name__ == "__main__":
     env = jinja2.Environment(
         loader=jinja2.FileSystemLoader(d),
         lstrip_blocks=True,
-        autoescape=False,
+        autoescape=select_autoescape(enabled_extensions=('html', 'xml')),
         keep_trailing_newline=True,
     )