vpython3: Add Python3 bin dir to PATH on Windows
vpython3: Add Python3 bin dir to PATH on Windows

As a workaround, add the Python3 bin dir to PATH so that the necessary DLLs are available.

Bug: 1003139
Change-Id: I7b3e05922be3fcb7b0ec2b06783a86f25484310b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1992270
Reviewed-by: smut <95deb7aa15d4c615299e47e7688551456568b1fb@google.com>
Commit-Queue: Edward Lesmes <d05609f027dc667cc37492b1dc1bdea5d60fa82a@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools