Remove commons-io from BUILD dependencies

commons:io is now provided as part of the Gerrit build plugins
dependencies.

Change-Id: Ie9c9fc024fbf3afcf7ccbc205dabd6aa8a3c8856

BUILD

diff --git a/BUILD b/BUILD
index 82ba9ba..949c290 100644
--- a/BUILD
+++ b/BUILD
@@ -18,7 +18,6 @@
 )
 
 TEST_DEPS = PLUGIN_DEPS + PLUGIN_TEST_DEPS + [
-    "@commons-io//jar",
     "@mime-types//jar",
     "@juniversalchardet//jar",
     ":uploadvalidator__plugin",