MAINTAINERS: git://github.com -> https://github.com for nilfs2

Github deprecated the git:// links about a year ago, so let's move to the
https:// URLs instead.

Link: https://lkml.kernel.org/r/20221020024255.5000-1-konishi.ryusuke@gmail.com
Link: https://github.blog/2021-09-01-improving-git-protocol-security-github/
Link: https://lkml.kernel.org/r/20221013214638.30933-1-palmer@rivosinc.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>