Specify the interpreter to run to avoid issues with several
python installations on Windows.

Bug: 1036606

Change-Id: Ib70d041acc52c940711460219acd8f4ad58637a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1992608Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>