Add proposed patch to fix test failures with gobject-introspection 1.81.x
Closes: #1081701
Thanks: Emmanuele Bassi
This passes tests with the old gobject-introspection (1.80.x in testing/unstable) and also with the new version (1.81.x in experimental).
I haven't done any manual testing with dependent packages: I don't know which ones, if any, use this particular pattern.