Upgrade transifex client

[rhiaro]

Overview

• What does this pull request do?

Updates all dependencies and the transifex config to be compatible with the newest transifex client.

Not much has changed. Transifex client is no longer a python dependency, and now needs to be installed with a curl command.

Resources on bods-main on transifex are updated to match what is currently in main. For any more schema/codelist/docs changes, the extract and pull steps will need to be run again.

• How can a reviewer test or examine your changes?

Reinstall dependencies in a new environment, and follow the instructions in BODS Dev Handbook PR https://github.com/openownership/bods-dev-handbook/pull/64

• Who is best placed to review it?

Closes #428

Translations

• [x] New or edited strings appearing as a result of this PR will be picked up for translation

Documentation & Release

• [x] I've checked that the documentation builds without failing. See: https://github.com/openownership/data-standard#building-the-documentation-locally
• [ ] I've thought about how and when this needs to be released. See: https://openownership.github.io/bods-dev-handbook/standard_releases.html
• [ ] I've updated the changelog, if necessary.
• [x] I've updated reference.rst to reflect any changes to schema structure or naming.
• [x] I've added or edited any other related documentation. See: https://github.com/openownership/bods-dev-handbook/blob/master/style_guide.md