Update submodules: plugins (new commits)

plugins:
    1293c1a Chris Smith <chris@dmdirc.com>
            Hit me with your deprecation stick.

            (Hit me slowly, hit me quick.)

            Gerrit: http://gerrit.dmdirc.com/3039

Change-Id: I6bf2a097c7dbb54e631cd2e8e13f411df374428f