websockify was added to the pip requires, and it has a dependency
of numpy. Because we didn't specify it in the package list, it was
built from source every time, adding 3 minutes to an average run.
Stop testing whether numpy compiles 100 times a day in CI.
Change-Id: Ic9d9b8135a917deb846911c6b266aec87d05781a
74c67fd861