gtk4: Update to 3.99.3+8880e3bd
gtk4: Update to 3.99.3+8880e3bd

Fixes https://gitlab.gnome.org/GNOME/vala/issues/1089

frida/vala,frida/vala,GNOME/vala,frida/vala,frida/vala,GNOME/vala,GNOME/vala,GNOME/vala,frida/vala