DEVELOPERS: remove Jonathan Liu

In a private e-mail answering one of our notifications about packages
being outdated, Jonathan replied:

"""
I switched from Buildroot to OpenEmbedded in 2013 so am no longer actively
involved with Buildroot.
Please unsubscribe me from outdated package notifications.
"""

So let's remove him from the DEVELOPERS file.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 175c3f8b2dde867d878f5a1eb01e8317257efd20)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

DEVELOPERS

@@ -1213,10 +1213,6 @@ F:	package/phidgetwebservice/
 F:	package/rapidxml/
 F:	package/sphinxbase/
 
-N:	Jonathan Liu <net147@gmail.com>
-F:	package/python-meld3/
-F:	package/supervisor/
-
 N:	Jörg Krause <joerg.krause@embedded.rocks>
 F:	board/lemaker/bananapro/
 F:	configs/bananapro_defconfig