nilfs2: MAINTAINERS: drop unreachable project mirror site

The hosting site where the nilfs project had a mirror site continues to be
in trouble, so we have decided not to use that site.  This will reflect it
in the MAINTAINERS file.

Link: https://lkml.kernel.org/r/20240208093018.6334-1-konishi.ryusuke@gmail.comSigned-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

MAINTAINERS

@@ -15435,7 +15435,6 @@ M:	Ryusuke Konishi <konishi.ryusuke@gmail.com>
 L:	linux-nilfs@vger.kernel.org
 S:	Supported
 W:	https://nilfs.sourceforge.io/
-W:	https://nilfs.osdn.jp/
 T:	git https://github.com/konis/nilfs2.git
 F:	Documentation/filesystems/nilfs2.rst
 F:	fs/nilfs2/