Add HOME env variable to cloudbuild so vpython can move forward.

Bug: skia:9348
Change-Id: Ic9d835f38b028c9a60f07b56f52527bcb440c454
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/236918
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Joe Gregorio <jcgregorio@google.com>
1 file changed