pidgin/pidgin

Add a missing transfer annotation to purple_history_manager_get_active

Testing Done:
Build `libpurple/Purple-3.0.gir` and verified the warning was gone.

Reviewed at https://reviews.imfreedom.org/r/1041/
libpurple/data/purple-url-handler.desktop.in
libpurple/protocols/null/nullprpl.c
pidgin/data/im.pidgin.Pidgin.desktop.in
sub/libpurple/data/purple-url-handler.desktop.in
sub/libpurple/protocols/null/nullprpl.c
sub/pidgin/data/im.pidgin.Pidgin.desktop.in