Make sysopen python3

Seems to already be python3, not sure if it is used, but it is mentioned
in documentation.

Change-Id: I34913a41f92b84091df8667e5046e270906aa141
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/842485
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: Ben Wagner <bungeman@google.com>
1 file changed