Upgrade weblate to 4.16.4

[robe]

We are currently at 4.15.2, which is the latest for 4.15 series.

4.16.4 was released today.

4.16 offers:

    Dependency updates
    Format string checks now also detects duplicated formats.
    Improved search performance for some specially formatted strings.
    Celery beat is now storing the tasks schedule in the database.
    Added support for IBM Watson Language Translator.
    Dropped support for VCS integration settings deprecated in 4.14.
    Added support for Bitbucket Server pull requests.
    Improved conflicts handling in gettext PO files.
    Added support for defining strings state when adding via API.
    Added support for configuring CORS allowed origins.
    Added plurals support to automatic suggestions.
    Added support for go-i18n v2 JSON files.

and numerous dependency updates

Need to check the VCS integration settings piece to make sure it doesn't break our install.

[robe]

Looks like we are using GITHUB_USERNAME / TOKEN and GITEA_USERNAME/TOKEN instead of recommended CREDENTIALS, so will need to change this before we can upgrade.

[robe]

Nevermind looks like the docker _USERNAME and _TOKEN do map to the new _CREDENTIALS settings. But I had to define a _HOST. Hopefully I did that right.