Bump Buildifier version to 2.2.1

Change-Id: I9876db8c2017a30967fc4eec781765d7e281ea62
diff --git a/jenkins-docker/slave-bazel-nocache/Makefile b/jenkins-docker/slave-bazel-nocache/Makefile
index e4a3c4e..a858fc4 100644
--- a/jenkins-docker/slave-bazel-nocache/Makefile
+++ b/jenkins-docker/slave-bazel-nocache/Makefile
@@ -1,7 +1,7 @@
 NO_CACHE=false
 IMAGE=gerritforge/gerrit-ci-slave-bazel:debian-stretch-nocache
 BAZEL_VER=2.2.0
-BUILDIFIER_VER=2.0.0
+BUILDIFIER_VER=2.2.1
 BAZELISK_VER=1.1.0
 NODE_VER=10
 WCT_VER=6.8.0