Old observations updated without substantive changes are changed to Purple

[nigelcharman]

The observations were originally RED. They had additional detail added to Weed Management Aotearoa NZ observation fields, but without the Date Controlled or Date of Status Update being set.

The status should have stayed RED but was changed to PURPLE.

See logs in https://github.com/EcoNet-NZ/inaturalist-to-cams/actions/runs/7951343326/job/21704656554 for details of the fields.

The issue seems to arise from translator.py:

        if visit_date < start_of_this_weed_year:
            visit_status = 'PURPLE'

[nigelcharman]

I'm not sure why these are updating the existing weed visit to Purple rather than creating a new weed visit?
Additional examples are weed instance 61124 and 61125.

[nigelcharman]

It's updating the existing weed visit row since the date hasn't changed.
Options to resolve this issue include:

1. Never set PURPLE status from the iNaturalist sync process
2. Only set PURPLE status on the initial synchonisation

The reason we are setting PURPLE currently is that we don't know the status of the observation. It may be years old and so we set it to PURPLE (needs checking).