Migrate build to python 3

Update the python version required in local scripts and in bazlets.

bazlets log:
$ git log --no-merges --oneline ^a52e3f381 00a97f961
b2b8548 download to GERRIT_CACHE_HOME when set
2d0cc7e Migrate to python 3
6311520 tools/maven/package.bzl: Use bazelisk instead bazel

Change-Id: I7a0671a0971ac91257ebca0aee8f8710dd5544a1

.bazelrc

diff --git a/.bazelrc b/.bazelrc
index 3ae03ff..f9248ea 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -1,2 +1,2 @@
-build --workspace_status_command="python ./tools/workspace_status.py"
+build --workspace_status_command="python3 ./tools/workspace_status.py"
 test --build_tests_only

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 5e94b73..c5c1061 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "a52e3f381e2fe2a53f7641150ff723171a2dda1e",
+    commit = "00a97f96162f06119021372f24e8a77d196079e1",
 )
 
 load(

tools/workspace_status.py

diff --git a/tools/workspace_status.py b/tools/workspace_status.py
index fa4f1e9..067d262 100644
--- a/tools/workspace_status.py
+++ b/tools/workspace_status.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # This script will be run by bazel when the build process starts to
 # generate key-value information that represents the status of the