ansible: install V8 build deps for Python 3

[richardlau]

Ensure httplib2 and six modules are installed for Python 3 on machines with the build-test-v8 role.

Refs: nodejs/node#48728
Refs: nodejs/node#48710 (comment)

[richardlau]

This came about because in trying to address nodejs/node#48728 by updating fetch_deps.py to use Python 3 we got other errors complaining about missing httplib2 and six:
https://ci.nodejs.org/job/node-test-commit-v8-linux/5435/

• https://ci.nodejs.org/job/node-test-commit-v8-linux/5435/nodes=rhel8-s390x,v8test=v8test/console

12:43:45 + ../../tools/v8/fetch_deps.py .
12:43:45 Cloning into '/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools'...
12:43:54 Traceback (most recent call last):
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gclient.py", line 108, in <module>
12:43:54     import gclient_scm
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gclient_scm.py", line 29, in <module>
12:43:54     import gerrit_util
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gerrit_util.py", line 16, in <module>
12:43:54     import httplib2
12:43:54 ModuleNotFoundError: No module named 'httplib2'
12:43:54 Checking out depot_tools.
12:43:54 Traceback (most recent call last):
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/../../tools/v8/fetch_deps.py", line 100, in <module>
12:43:54     FetchDeps(sys.argv[1])
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/../../tools/v8/fetch_deps.py", line 72, in FetchDeps
12:43:54     depot_tools = node_common.EnsureDepotTools(v8_path, True)
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/tools/v8/node_common.py", line 40, in EnsureDepotTools
12:43:54     depot_tools = _Get(v8_path)
12:43:54   File "/home/iojs/build/workspace/node-test-commit-v8-linux/tools/v8/node_common.py", line 35, in _Get
12:43:54     subprocess.check_output(
12:43:54   File "/usr/lib64/python3.9/subprocess.py", line 424, in check_output
12:43:54     return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
12:43:54   File "/usr/lib64/python3.9/subprocess.py", line 528, in run
12:43:54     raise CalledProcessError(retcode, process.args,
12:43:54 subprocess.CalledProcessError: Command '['/usr/bin/python3', '/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gclient.py', 'metrics', '--opt-out']' returned non-zero exit status 1.
12:43:54 make: *** [Makefile:303: v8] Error 1

• https://ci.nodejs.org/job/node-test-commit-v8-linux/5435/nodes=rhel8-ppc64le,v8test=v8test/console

12:43:29 + ../../tools/v8/fetch_deps.py .
12:43:29 Cloning into '/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools'...
12:43:37 Traceback (most recent call last):
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gclient.py", line 108, in <module>
12:43:37     import gclient_scm
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gclient_scm.py", line 29, in <module>
12:43:37     import gerrit_util
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gerrit_util.py", line 37, in <module>
12:43:37     from six.moves import urllib
12:43:37 ModuleNotFoundError: No module named 'six'
12:43:37 Checking out depot_tools.
12:43:37 Traceback (most recent call last):
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/../../tools/v8/fetch_deps.py", line 100, in <module>
12:43:37     FetchDeps(sys.argv[1])
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/../../tools/v8/fetch_deps.py", line 72, in FetchDeps
12:43:37     depot_tools = node_common.EnsureDepotTools(v8_path, True)
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/tools/v8/node_common.py", line 40, in EnsureDepotTools
12:43:37     depot_tools = _Get(v8_path)
12:43:37   File "/home/iojs/build/workspace/node-test-commit-v8-linux/tools/v8/node_common.py", line 35, in _Get
12:43:37     subprocess.check_output(
12:43:37   File "/usr/lib64/python3.9/subprocess.py", line 424, in check_output
12:43:37     return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
12:43:37   File "/usr/lib64/python3.9/subprocess.py", line 528, in run
12:43:37     raise CalledProcessError(retcode, process.args,
12:43:37 subprocess.CalledProcessError: Command '['/usr/bin/python3', '/home/iojs/build/workspace/node-test-commit-v8-linux/deps/v8/_depot_tools/gclient.py', 'metrics', '--opt-out']' returned non-zero exit status 1.
12:43:37 make: *** [Makefile:303: v8] Error 1