Setting different timestamp?

[vexillia]

Trying to config this to use an rss feed from blogger. The timestamp is causing me a few problems.

RSS timestamp
2024-01-07T15:00:00.005+00:00

Linux date equivalent:
date +%Y-%m-%dT%H:%M:%S.%3N%z

Setting date under Dynaconf section in rss2bsky/lib/python3.12/site-packages/rss2bsky/main.py to

DATE_FORMAT="%Y-%m-%dT%H:%M:%S.%3N%z"

Produces this error:

File "/home/vexillia/.local/share/pipx/venvs/rss2bsky/lib/python3.12/site-packages/rss2bsky/main.py", line 108, in main
    datetime.strptime(start_post_date_str, settings.DATE_FORMAT)
  File "/usr/lib/python3.12/_strptime.py", line 554, in _strptime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/_strptime.py", line 325, in _strptime
    raise ValueError("'%s' is a bad directive in format '%s'" %
ValueError: '3' is a bad directive in format '%Y-%m-%dT%H:%M:%S.%3N%z'

So how do I set the appropriate date format?

Thanks.