MAINTAINERS: mention my gdbstub/next tree

Make it easy for people to see what is already queued.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20241023113406.1284676-12-alex.bennee@linaro.org>

MAINTAINERS

@@ -2984,6 +2984,7 @@ F: gdb-xml/
 F: tests/tcg/multiarch/gdbstub/*
 F: scripts/feature_to_c.py
 F: scripts/probe-gdb-support.py
+T: git https://gitlab.com/stsquad/qemu gdbstub/next
 
 Memory API
 M: Paolo Bonzini <pbonzini@redhat.com>