[weblate] New enricher to handle changes

[zhquan]

This code proposes a new weblate enricher to handle changes including their units and author information.

Demography study included.

The new enricher is added to the list of connetors and can be defined in the mordred setup.cfg as follows:

[weblate]
raw_index = weblate_chaoss_raw
enriched_index = weblate_chaoss_enriched
api-token= ...
no-archive = true
sleep-for-rate = true
studies = [enrich_demography:weblate]

[enrich_demography:weblate]

projects.json

{
  "chaoss": {
    "weblate": [
      "my.weblate.org"
    ]
  }
}

Tests added accordingly.

Signed-off-by: Quan Zhou quan@bitergia.com