MAINTAINERS: Add @cyphar as maintainer

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

Author: giuseppe

MAINTAINERS

@@ -4,3 +4,4 @@ Vincent Batts <vbatts@redhat.com> (@vbatts)
 Daniel, Dao Quang Minh <dqminh89@gmail.com> (@dqminh)
 Tianon Gravi <admwiggin@gmail.com> (@tianon)
 Qiang Huang <h.huangqiang@huawei.com> (@hqhq)
+Aleksa Sarai <asarai@suse.de> (@cyphar)