Merge branch 'stable-3.1' into stable-3.2

* stable-3.1:
  Bump Bazel version to 3.5.0
  Upgrade bazlets to latest stable-3.1 to build with 3.1.8 API
  Upgrade bazlets to latest stable-3.0 to build with 3.0.12 API
  Upgrade bazlets to latest stable-2.16 to build with 2.16.22 API

Change-Id: I81021fc7cab8cfb0a04337f1ee6568203ba70a0f

.bazelversion

diff --git a/.bazelversion b/.bazelversion
index 47b322c..1545d96 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-3.4.1
+3.5.0