Bump buildfier version to 3.0.0

Change-Id: I79d8b20cd5a3a664b2fb81d1fcd0757f33f45bfa
diff --git a/jenkins-docker/slave-bazel-nocache/Makefile b/jenkins-docker/slave-bazel-nocache/Makefile
index 5336744..45d96b5 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=3.1.0
-BUILDIFIER_VER=2.2.1
+BUILDIFIER_VER=3.0.0
 BAZELISK_VER=1.4.0
 NODE_VER=10
 WCT_VER=6.8.0