AdwApplication: Fix memory leak in update_stylesheet
requested to merge julianrichen/libadwaita:adw-application-fix-update-stylesheet-memory-leak into main
GtkSettings::gtk-theme-name, or any property returned by GtkSettings' get_property, is g_value_copy-ed to the provided variable (theme_name). Switching const char to a g_autofree gchar * to automatically free the variable once out of scope.
Seems to have fix one of the leaks I found while testing my application.