Explicitly set python version for pylint 2.6

vpython doesn't parse shebang. If python version is not explicitly set
in vpython file, version 2 will be used. pylint 2.6 requires py3.

R=dpranke@google.com

Bug: 1242737
Change-Id: I21a3c4b26c24860b4c8fd07c6d5cc6d5149af2fc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3120321
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

presubmit_canned_checks.py

@@ -973,7 +973,7 @@ def GetPylint(input_api,
     return []
   files.sort()
 
-  input_api.logging.info('Running pylint on %d files', len(files))
+  input_api.logging.info('Running pylint %s on %d files', version, len(files))
   input_api.logging.debug('Running pylint on: %s', files)
   env = input_api.environ.copy()
   env['PYTHONPATH'] = input_api.os_path.pathsep.join(extra_paths_list)

pylint-2.6

@@ -9,6 +9,7 @@
 # [VPYTHON:BEGIN]
 # # Third party dependencies.  These are only listed because pylint itself needs
 # # them.  Feel free to add/remove anything here.
+# python_version: "3"
 #
 # wheel: <
 #   name: "infra/python/wheels/futures-py2_py3"
@@ -32,7 +33,7 @@
 # >
 # wheel: <
 #   name: "infra/python/wheels/wrapt/${vpython_platform}"
-#   version: "version:1.10.11"
+#   version: "version:1.12.1"
 # >
 # wheel: <
 #   name: "infra/python/wheels/lazy-object-proxy/${vpython_platform}"