Template.render changelog is documented as using asyncio.run but does not

[graingert]

this was supposed to be introduced in #1444

but actually uses asyncio.new_event_loop().run_until_complete() https://github.com/pallets/jinja/pull/1444/files#diff-8cc12d19725f1da7bcad40d7f4fda3c343cc7e1ed7cc69a09e48be8bd2abf636R1290