use cipd package for python on skcms bots

I've had to rm gen_tasks.go.  I can't run it any more because of some
sort of Golang dependency hell.  It doesn't really do much anyway...
easy enough to just edit tasks.json.

Change-Id: Idc1c0afdee2078f2fa9755fe7c5725bb249d8f79
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/247052
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed