Update submodules: plugins (new commits)

plugins:
    73cefb0 Greg Holmes <greg@dmdirc.com>
            Keep serverlist stuff in ServerLists!

            Gerrit: http://gerrit.dmdirc.com/3851

Change-Id: Iace8cb7123ff626e4fbd5dbf04e5d560d6b95b77

modules/plugins

@@ -1 +1 @@
-Subproject commit 93d405608c0e125084edcda94239189787e751da
+Subproject commit 73cefb08054b36e39eb0533ec9e7107ac68ee53f