Format external_plugin_deps.bzl with buildifier

Change-Id: Ic654b81b5f91726fecc0599d96ff06f75d0e8c07
diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index bd864bf..f776db8 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -35,4 +35,4 @@
         name = "commons-io",
         artifact = "commons-io:commons-io:2.6",
         sha1 = "815893df5f31da2ece4040fe0a12fd44b577afaf",
-   )
+    )