Deprecation of XML RPC API by december 2023

[vankasteelj]

XML RPC API will be deprecated by december 2023. Updates are needed (branch REST already started)

see https://forum.opensubtitles.org/viewtopic.php?f=11&t=17930

[vankasteelj]

This is a REST alternative I'm developping: https://github.com/vankasteelj/opensubtitles.com

Sadly, the calls are very limited atm.