Add missing PLUGIN_DEPS

Change-Id: Ie66c0198ad4127f357ce214d3616048f19108223
diff --git a/tools/bzl/plugin.bzl b/tools/bzl/plugin.bzl
index 2b1df8c..c157125 100644
--- a/tools/bzl/plugin.bzl
+++ b/tools/bzl/plugin.bzl
@@ -1,4 +1,5 @@
 load(
     "@com_googlesource_gerrit_bazlets//:gerrit_plugin.bzl",
+    "PLUGIN_DEPS",
     "gerrit_plugin",
 )