Generated by `pyupgrade --py3-plus --keep-percent-format` on all our
Python code except `zthumbor` and `zulip-ec2-configure-interfaces`,
followed by manual indentation fixes.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
IFTTT allows custom templating for their payloads, so the onus is
on the user to ensure that their custom templates conform to the
expectations outlined in our IFTTT webhook docs. For that reason,
these payloads weren't generated, but were manually edited.
