DEVELOPERS: remove Min Xu

Min Xu has said at
https://patchwork.ozlabs.org/project/buildroot/patch/20220519074438.462-1-xuminready@gmail.com/
that they are no longer interested in maintaining this package, so
drop them from the DEVELOPERS file.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

DEVELOPERS

@@ -2092,9 +2092,6 @@ F:	configs/bananapi_m2_plus_defconfig
 N:	Mikhail Boiko <mikhailboiko85@gmail.com>
 F:	package/libfribidi/
 
-N:	Min Xu <xuminready@gmail.com>
-F:	package/shadowsocks-libev/
-
 N:	Miquèl Raynal <miquel.raynal@bootlin.com>
 F:	package/mali-driver/
 F:	package/rockchip-mali/