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
  Bump Bazel version to 3.0.0

Change-Id: Ie282d48781eb92ec9e3243eec7a0663b3fec9265

.bazelversion

diff --git a/.bazelversion b/.bazelversion
index ccbccc3..fd2a018 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-2.2.0
+3.1.0