[infra] Fix Windows OS dimension to match main branch

Change-Id: Ib880a979354e467190163c9f77e611617584e8b7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/644876
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Commit-Queue: Eric Boren <borenet@google.com>