Bug#955099: libmypaint: FTBFS with Sphinx 2.4: TypeError: parse_declaration() missing 1 required positional argument: 'directiveType'

[Jesper Lloyd]

Building the docs with sphinx 2.4 and the latest python3-breathe
(3.14.1) seems to work fine (-ish; 8 warnings, no errors). I don't
think the problem can be fixed in libmypaint's sphinx configuration.