Adapt to bazel 9.1.0 update

Change-Id: I59d79f0a9ad35bc1184bd4c3ba5901f380e60246

BUILD

diff --git a/BUILD b/BUILD
index 47e36c1..ad3220e 100644
--- a/BUILD
+++ b/BUILD
@@ -4,6 +4,7 @@
     "gerrit_plugin_test_util",
     "gerrit_plugin_tests",
 )
+load("@rules_java//java:defs.bzl", "java_library")
 
 PLUGIN = "healthcheck"