Merge branch 'stable-3.1'

* stable-3.1:
  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
  Bump Bazel version to 3.4.1

Change-Id: I86098f5a079d9fa9e4a2418bce51b0466c6b1563