MAINTAINERS: remove Gilles Muller

Gilles Muller passed away on November 17, 2021.  We would like
to thank him for his continued support for the development of
Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

MAINTAINERS

@@ -4685,7 +4685,6 @@ F:	drivers/media/pci/cobalt/
 
 COCCINELLE/Semantic Patches (SmPL)
 M:	Julia Lawall <Julia.Lawall@inria.fr>
-M:	Gilles Muller <Gilles.Muller@inria.fr>
 M:	Nicolas Palix <nicolas.palix@imag.fr>
 L:	cocci@inria.fr (moderated for non-subscribers)
 S:	Supported