tools: windows_boxstarter "choco install python -y" for Python 3

PR-URL: https://github.com/nodejs/node/pull/26424
Refs: https://github.com/nodejs/node/issues/25789#issuecomment-469238697


Reviewed-By: Bartosz Sosnowski <bartosz@janeasystems.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>