Merge branch 'stable-3.0' into stable-3.1

* stable-3.0:
  Upgrade bazlets to latest stable-2.16 to build with 2.16.18 API
  Bump Bazel version to 3.1.0

Change-Id: Ic62a32c80078104312ab0b2522b8211aa8f996db
diff --git a/.bazelversion b/.bazelversion
index 4a36342..fd2a018 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-3.0.0
+3.1.0