docstring on_failure description does not match function

[mark-walle]

I think that these docstrings:

snowplow-python-tracker/snowplow_tracker/emitters.py

Line 88 in 91da00a

:param on_failure: Callback executed if at least one HTTP request in a flush has status code 200

snowplow-python-tracker/snowplow_tracker/emitters.py

Line 347 in 91da00a

:param on_failure: Callback executed if at least one HTTP request in a flush has status code 200

should read something closer to:

Callback executed if at least one HTTP request in a flush has status code other than 200

Noting that this ignores the range suggested in is_good_status_code(status_code) since the docstring for on_success also ignored it.

[BenFradet]

good catch 👍 , feel free to open a pr

[mark-walle]

PR #217