git: update to v2.56.0

Update to git version v2.56.0, this requires a change for this
upstream commit:

* 88d06b1c911e8491029ef24e96e3f412ce24c2ae
  pathspec: match and original in pathspec_item are const

Signed-off-by: Christian Hesse <mail@eworm.de>
Reviewed-by: John Keeping <john@keeping.me.uk>