Enable buildifier presubmit check

.bazelci/presubmit.yml

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index d529df1..67277a4 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -1,4 +1,5 @@
 ---
+buildifier: latest
 tasks:
   ubuntu1604:
     build_targets: