The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
GObject-Introspection XML files
/usr/share/gir-1.0/Foo-23.gir) must be made available in
a development package in the
libdevel section of the archive.
This is normally the same
libfoo-dev package that contains
other development files.
Refer to /usr/share/doc/gobject-introspection/policy.txt for details.