git-remote-mediawiki: use --force when adding notes

git-remote-mediawiki: use --force when adding notes

When notes are created to record a push, it normally doesn't exist yet.
However, when a push is interrupted and then restarted, it may happen
that a commit already has notes attached, and we want to reflect the newly
created remote revision, hence use 'git notes add -f' to override the
existing one

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>