[test] Print Python version that's running on bots

Bug: v8:9871
Change-Id: I66976c3490ec9fd732f99a8500bae9925bb89446
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2953185
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Reviewed-by: Liviu Rau <liviurau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75091}

tools/testrunner/base_runner.py

@@ -284,6 +284,11 @@ class BaseTestRunner(object):
         # this less cryptic by printing it ourselves.
         print(' '.join(sys.argv))
 
+        # TODO(machenbach): Print used Python version until we have switched to
+        # Python3 everywhere.
+        print('Running with:')
+        print(sys.version)
+
         # Kill stray processes from previous tasks on swarming.
         util.kill_processes_linux()