[Urgent] Update Transifex Calls to APIv3

See notice at the top of https://docs.transifex.com/api/introduction

This tool will no longer be functional as of April 7th.

Whoops, I incorrectly assumed this tool made calls to the transifex api. After digging through the source, this does not seem to be the case.

Thanks for your reporting!

As you are aware, sphinx-intl does not call transifex-api. However, it uses transifex-client, which is deprecated in accordance with the API.

sphinx-intl/setup.py

Lines 14 to 17 in 6edc8aa

    
           extras_require = { 
        
               'transifex': [ 
        
                   'transifex_client>=0.11' 
        
               ],

https://docs.transifex.com/client/introduction

Therefore, we need to switch to calling the new transifex cli by the end of 2022.

@shimizukawa Actually, sphinx_intl/transifex.py seems to import txclib.utils, so it also relies on a Python library (the one that will sunset soon) that will not be available in the new golang implementation of the CLI tool.