telepathy-ring ftbfs in focal

telepathy-ring ftbfs in focal. the version in -proposed is needed for the python removal.

https://launchpad.net/ubuntu/+source/telepathy-ring/2.3.24-1ubuntu1

ring-call-stream.c: In function ‘ring_call_stream_request_receiving’:
In file included from ring-call-content.c:27:
../ring-extensions/ring-extensions.h:4:10: fatal error: ring-extensions/_gen/svc.h: No such file or directory
    4 | #include "ring-extensions/_gen/svc.h"
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
ring-call-stream.c:74:3: warning: ‘tp_errors_quark’ is deprecated: Use 'TP_ERROR' instead [-Wdeprecated-declarations]
   74 | GError error = { TP_ERRORS, TP_ERROR_NOT_IMPLEMENTED,
      | ^~~~~~
compilation terminated.